It sounds like you iac on your tb isn't letting air past the butterfly valve. I would test the resistance across the pins on the iac solenoid. The pins are numbered 1-4 from left to right and the resistance acoss 1&4 should be 35-52 ohms and the resistance across pins 2&3 should be 28-52 ohms. Hope this helps.

96' eclipse gs, 2gb conversion
built bottom end, crane #16 cams, hx40 pro billet, MS1 v3 MSn'S-E, 3.55 trans, quaife lsd