Well, I've got a few idea's but check for error codes first:
http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx
Then I'd check for intake leaks, test the ECU coolant temp sensor, test the AFM and test the fuel pressure.
Does this happen whenever you start the car or just when it's (the engine) cold? So, if it is 32? outside and you've been driving around... you stop, turn off the engine, run into the gas station for your favorite pr0n and come back out... does it start right back up or does it still falter?