Crack open your ECU first and have a look at the capacitors/general condition of it. Might save you a few dollars rather than buying random parts on a hunch.

Yeah, I've had numerous non Mr2 mechanics suggest the ECU is at fault... only to later find out they have all been perfectly fine.  PLEASE do as others have advised, have a reputable specialist look at it.
 

jsnhrl
It could be the ECU. I had similar symptoms.
 
Mine went about 4 years back. One of the capacitors inside were leaking. Symptoms were the engine would just turn off while driving, independent of anything else (speed, load, rpm, boost etc). The speed and tach would drop to zero and the engine would stop. Because the ignition was set to "on" when the engine shut off, the dash lights would be active - I never lost power (ie. radio, lights etc.) but the engine stops because there is no spark/fuel.
 
After sitting overnight and having a cold start, the first time it would turn off 20-40 minutes after driving, then 10, then 5. It would progressively decrease that time until it would just crank over and not start. ie the more "warmed up" the car was, the more prone it was to shutting off.
 
 

Seems people are divided on the ecu...  2 years ago I would've been doubtful too but I've had the exact prob as the above quote in an extremely low mileage  Bathurst, showing age is definitely an issue now.   I initially replaced both the Ignitor and Coil with no change in the symptoms.  A few screws and a quick inspection turned up two leaky caps, should've done this first but at the time I was thinking ~50,000km no way the ecu would be faulty.
 
Replacement ecu and its been peachy since.  Its an easy check man and takes under half an hour to check and reinstall if its not showing leaks.  Even if it doesn't look leaky I'd still try another ecu.  I replaced both leaky caps in mine and it took longer for the issue to show but still it came back.  Just my 2c.
 
Don't let this bad first experience turn you off these cars can be rewarding, best of luck.

Yeah they will charge you even if its fine. They will charge you a couple of hundred for looking at it. Plus your mechanics diagnostic costs etc...Then your mechanic will install it and realise that the car is still exactly the same. So eventually he will change the coil/ignitor and charge you for the whole lot.....(most likely, this is what I'm tipping will happen, I am strongly guessing its your coil or ignitor module). This car is a going to cost you a bit I'm thinking and cause you a lot of stress.
Hopefully it is the ECU at fault but his picked the most expensive thing first hoping its that.   

How did you go initialvin? How's the Mr2?

hey guys
thanks for the replies
 
finally after a week in the garage, my mr2 is at home :)
is drivable but need lots of work over a few weekends to get it running good
 
so yea the mechanic called me this afternoon and told me they got the ECU back from the repair centre,
plugged in and haven't stall since,
I was on my way there anyways to check of the hand brake cable problem,
 
arrived the mechanic also pointed out to me some issues underneath the car,
the hand brake cable to the left rear wheel is completely gone,
Ill order one asap from amayama.com
some dried and fresh oil leaks at the bottom of the engine 0.O
car had a front end crash and the chassis is bent and causing the radiator can't be fixed in place T.T
what is that thing in the 2nd photo, there is a cable sticking out of it.....
(noob question - whats the difference  radiator and front mount intercooler)
fog lights doesnt work and a ton of cables just laying around for me to fix later 
 
the mechanic told me he wants to run the car for a while long to see if the stalling had been fixed
and he changed the engine oil and gearbox oil for me
I left for lunch and went to RTA in merrylands to get the rego into my name
 
when I came back the car was ready for me
the mechanic drove me around for a while, chatted a bit, he told he got a sw20 too when it first came out,
the car seems fine - for now lol
we took it back to the garage and I was waiting to see the bill
he charged me $1000 all up
I was expecting that - $80 for towing and $400 for ECU fix by another company
new spark plugs, got me another battery, minor service,
 
I drove home without trouble, but can hear some noise from the wheels,
I think is those fake brembo brakes covers..... the prev. owner had on
 
so anyways, will see what happens when I drive the mr2 on the weekends
hope it won't be anymore headaches for me
is alright I guess, I get what I paid for, $5350 for a hardtop turbo with 10 months rego
I will try to work on some small thing over the weekends 
 
and I want to show up to the nationals lol
 
thank you so much
Vincent