Resource icon

Reference Troubleshoot Iac Idle Problems 1996-2004


SN Certified Technician
Aug 14, 2009
Houston Texas


New Member
Feb 7, 2014
I need some help: I have a 99 GT, 4.6 liter engine. Everything is absolutely original, except for accel coil packs. Whenever I coast in neutral the engine will sputter, try and regain it's Idle, then just dies. When I am just sitting there and havent touched the Throttle, the car typically does fine. But if I rev it ANY, the car will try and regain it's idle and eventually floods out. Okay, The catch:

I installed a brand new IAC Valve and I noticed a better start up - a not so "forced" start up (stubborn 4.6). Do I need to replace my MAF sensor? TPS? O2 Sensor? I have been dealing with this for about two weeks and I'm tired of risking a wreck on decelerating into turns. Also, I've heard lots of things as far as bad connections on certain electronics, if I put the dielectric grease on all my contacts (literally everything from censors, to fuses) would it make a difference?

At this point I would appreciate anyone's help.

-Confused Teenager