How bad is your fuel economy? 
Fill to the brim, drive 100km on open road, not stop start city driving, then re-fill.
I agree with Dwyer125, while the cam timing is possible, it is unlikely.

Hoonsy aren't you in qld?
Get to know the service manual to service all the normal service things, or meet with other mr2 owners to learn, or get a mechanic to do it if you don't have the tools.
Cam timing has to do with removing the timing cover to see the cam gears, using a timing light whilst the car is running. But that's only a basic check back to spec as per manufacturer. Retarding or advancing is best checked in a dyno to the benefits. My last one was advanced 15 from memory but done on a dyno.
If you want to know if you have the right air fuel mix (therefore the best fuel economy and possible power) get a dyno check test for under $100. You could need so many things but it's all guess work until you get it on a dyno. Could be things like injectors need an ultrasonic clean to spray better, could be the oil you are using.
All the best.

Your getting cam and ignition timing mixed up.

You dont remove any covers to check and set ignition timing when using a timing light.

Std ign timing is 10deg btdc.

Just_ace you remove the cam cover to see that the cams are correctly set with the timing belt. Check the cam is pointed at the factory mark, and ensure when the tensioner was released it didn't through a tooth out.
Yes check timing using the timing light, remove the cam cover to check they are not out.
Still the post doesn't list what's wrong ... So we are all guessing and time wasting :)

TwoDogs
How bad is your fuel economy? 
Fill to the brim, drive 100km on open road, not stop start city driving, then re-fill.
I agree with Dwyer125, while the cam timing is possible, it is unlikely.

Well it's pretty bad. I'm chilling just under 300kms so far to this one tank and I'm just a notch above 1/4 tank remaining.

I'd understand if it was forced induction but on a n/a 4cyl.. not so much

TonyMR2
Hoonsy aren't you in qld?
Get to know the service manual to service all the normal service things, or meet with other mr2 owners to learn, or get a mechanic to do it if you don't have the tools.
Cam timing has to do with removing the timing cover to see the cam gears, using a timing light whilst the car is running. But that's only a basic check back to spec as per manufacturer. Retarding or advancing is best checked in a dyno to the benefits. My last one was advanced 15 from memory but done on a dyno.
If you want to know if you have the right air fuel mix (therefore the best fuel economy and possible power) get a dyno check test for under $100. You could need so many things but it's all guess work until you get it on a dyno. Could be things like injectors need an ultrasonic clean to spray better, could be the oil you are using.
All the best.

Yeah I'm from QLD. Only one yellow SW20 on here so easy to keep track of haha

But just to clear up the air, the few things I have covered so far include checking ignition timing, changing spark plugs for new Bosch quad tip ones (not sure if I got the right ones, but fuel economy remained the same after changing), oil change to much higher quality full synthetic and Ryco filter, cleaned air filter (pod).. think that's most of it. My mechanic said he did my fuel filter a while back, but I don't know if he did as he never charged me for it (been a while since I went to him, he lost my engine prop stick.. $50 gone haha)

I'll have to get to the dyno sometime then. I've got cash set aside at the moment but I'm not ready to be throwing a few hundred dollars on diagnosing - I'll wait for an apprenticeship to swing my way first :)

One thing that you have not looked at is the oxygen sensor which plays a very important part in good fuel economy. This is the only sensor that gives feed back to the ECU so it can decide if the engine is running rich or lean.  Factory ECUs use an integrator which is a bi-product of the oxygen sensor's output (feedback) and it instantly pulls the desired AFR (air fuel ratio) to 14.7:1 which is good for fuel economy.  If the oxygen sensors output is lower than it should be due to old age the engine will be given the wrong feed back and over fueling will occur.  Sometimes an oxygen sensor can be poisoned by contaminants and the oxygen sensors output will by higher than normal causing a lean condition which can also cause all kinds of problems.  So an oxygen sensor's output voltage might be incorrectly high or low but as long as it is moving it is unlikely to set a fault code light.   It is for this reason a faulty oxygen sensor is often overlooked as very few mechanics if any, have tools good enough to test this sensor.
Usually only replaced when a faulty oxygen code is generated due to no output/movement from the sensor and the engine light comes on.
 
What you could do as a test.
 
Disconnect your oxygen sensor at it's 4 pin plug. Reset the ECU buy removing all power by disconnecting your battery for an hour or so.  This should allow the ECU to drop its' learnt memory data.  Reconnect battery and test drive for a full tank of fuel with oxygen sensor disconnected.   Yes the engine light should come on as your oxygen sensor is not seen buy the ECU.
 
Would be interesting to know your result.

FYI I was the previous owner. Now that I think about it, I was in the process of getting the thermostat changed when I did the coolant change. Have you had the thermostat replaced? I remember the temperature gauge took way too long to get warm, like 10 minutes. I'm not really clued in on MR2s, I've only ever worked on old school carburetor vehicles but maybe a low temp will cause excessive fuel consumption.

mr2y
FYI I was the previous owner. Now that I think about it, I was in the process of getting the thermostat changed when I did the coolant change. Have you had the thermostat replaced? I remember the temperature gauge took way too long to get warm, like 10 minutes. I'm not really clued in on MR2s, I've only ever worked on old school carburetor vehicles but maybe a low temp will cause excessive fuel consumption.

I haven't replaced it, but you're definitely right - the temp gauge takes a million years to reach proper temperature. I'm not sure if it'd affect fuel consumption however - I thought it was more of sensor regarding when engine bay fans should be turned on / a warning "gauge" in case the car overheats. It could, I don't know what I'm talking about, someone might be able to shed some light on it..

I'm definitely thinking its the o2 however - the car smells like crap from the exhaust after I park it after a 5-10min+ drive - not of fuel though. I don't know what 'lean' smells like but I'm feeling its that

I've got a replacement Denso o2 sensor (cheap eBay one), hoping it fits without issue. Need a hand getting it in though..