Well the idle on these cars r controlled by the computer. Check for error codes stored. Then check the TPS. U didn't play with the little screw of the throttle did u.
Tps test:
http://www.cygnusx1.net/Supra/Librar...spx?S=FI&P=101
Code test:
http://www.cygnusx1.net/Supra/Librar...ection=FI&P=23