When it will crank but not start try using a timing light on a high tension plug cable and see if the timing light is flashing which will at least indicate if it has spark.
If spark is present then it's bound to be lacking fuel.
Gain access under ashtray and check for 12 volt supply to fuel pump while engine is being cranked.
The slight misfire before stalling is indicative of an electrical interruption most likely to the fuel pump and a quick drop in fuel pressure.
Continue to be suspicious of that MAF connector too.

Falcon
When it will crank but not start try using a timing light on a high tension plug cable and see if the timing light is flashing which will at least indicate if it has spark.
If spark is present then it's bound to be lacking fuel.
Gain access under ashtray and check for 12 volt supply to fuel pump while engine is being cranked.
The slight misfire before stalling is indicative of an electrical interruption most likely to the fuel pump and a quick drop in fuel pressure.
Continue to be suspicious of that MAF connector too.

 
Do you know of any write up / guides to test for 12v to fuel pump when engine is being cranked? Would jumping FP and B+ in the diagnostic panel achieve the same thing?
 
Another issue the car has is long crank time (5secs) when cold. It starts quickly when warm. I assumed this was due to a faulty cold start sensor or cold start injector, but I suppose a dying fuel pump would explain both problems.
 
Fuel pump looks like a 5hr labour + parts kinda deal :(. Any pump recommendations? OEM Denso or Walbro 255?
thanks

Have you used timing light to check for spark while cranking? Do easy stuff first.
Jumping FP and B+ will not necessarily give the answer as that removes circuit opening relay etc. from the circuit.
Disconnect fuel pump coupling under ashtray and probe with multimeter for voltage while cranking engine.
It is important to do this as the fuel pump should only receive voltage initially while key is in the cranking position.
Once the engine is running it keeps the fuel pump circuit active but if engine stalls as in an accident then the circuit is opened to prevent fuel flow. Safety feature.
You may not have a fuel pump failure but more likely a problem in the relay or wiring of the circuit.
Check easy stuff first.  Changing the fuel pump is quite straight forward but it ain't fun and you will still have the same nasty guy hiding in the circuit somewhere.

I havent got a timing light so Ill have to ask my mechanic to test timing. I'm taking it in on Monday for other issues so I'll add it to my list. I live in an apartment and have limited tools / skills. I do have a multi-meter though.
 
Is the fuel pump connector the grey one shown below? One is for the fuel gauge but not sure which is which.

 
I'll see how I go testing what I can. I have a feeling it's a combo of fuel pressure, poor spark, bad leads, old dizzy, old igniter etc. I'll replace all of it eventually but at this stage I just want to fix the main culprit. Moving house soon and I need this thing to drive 
 
ta
 

Yes. Grey coupling is fuel pump. Timing light is to just ascertain that spark is occurring during cranking. Not to check ignition timing as engine wouldn't run if it was off badly.
One thing at a time.  I have a feeling it's just one thing happening intermittently as the engine runs correctly until this problem shuts it down. That is why I have suggested to check for spark while it is playing up to rule that out first.
 

It's your ignitor module or ignition coil.

Possibly faulty ECU capacitors also. Read through the thread below.
 
http://www.mr2oc.com/6-mkii-90-99-na-turbo/559625-ecu-capacitor-replacement-how-guide.html
 
I have a spare ecu here that was doing weird things a year or two ago and just swapped it out for a different one. Opened it up last night and found two blown caps. I am goign to do a repair so I have a spare ECU again.

I will put money on it. It's the ECU. Cap will work for a while until ECU is heated up, then they fail.
This is a link which will show you I went through the exercise with my Mr2.
https://www.mr2australia.com/mr2play/tm.aspx?m=132739
 

Thanks I'll take a look at the ecu

Prelim results are in:
 
- I could hear the fuel pump when jumping FP and B+ in the diagnostic port
- There was 11v at the grey ashtray fuel pump coupling when cranking
 
So i guess this rules out a fuel issue? It was stalling at around 1,500 rpm so the pump wasn't under load at the time, and everything seams to be powering properly. 
 
I also checked the cold start sensor. BGB provides two tests.
1. Resistance of 70 - 90 ohm between the two terminals. Mine scored 77ish 
2. Resistance of 30 - 90 ohm between STA(?) and ground. One of the terminals to ground was 147, and the other was 75. I'm not sure which is which so this could either be a pass or fail. I'll get a second opinion on this one.
 
I haven't checked the ECU yet but I'll take a look this weekend. At this stage I'm thinking it's ignitor, distributor, or ecu.
 
thanks for the help so far