This would have gotten more attention if it was in the correct forum. In the future you'll want to refer to the MKIII section. Thread moved.
The AFM and ECU coolant temp sensors are the first two components I would test. The ECU's are old and often benefit from rebuilding (replacing the old electrolytic capacitors which deteriorate and often leak at this age) but they're seldon the cause of significant operational problems. Also, the MKIII has always been a richly tuned engine... Toyota's performance vehicles often were back then.
__________________
If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum.
If you're so inclined I'm always more than happy to accept tips via PayPal. 
Tip Jar ---> 
|