heres how I check for leaks in the intake. Just cap the TB with your hand, the motor should die instantly, if it doesnt or tries to still run you have a vac leak somewhere. If it does shut off then I would start looking to the IAC since the air must be bypassing the throttle plate.

98 Eclipse GS Turbo
Built motor - MS2 - Holset hy35 - Zoom Stg 4 Clutch - 57.5mm TB - ARP Headstuds - Turbonetics wastegate - 3" Turbo back - FMIC - Greddy RZ BOV - Walbro 255 - 650cc Injectors - Fidanza Flywheel - Cobra calipers w/ 13" Rotors - Oil Cooler - DevilsOwn meth injection

1981 Chevy Scottsdale
1987 Nissan 300zx - Chump Car
2001 BMW 325i