Idle Problems

[arcwcb]

My gf has a 2000 GT auto, and within the last year, it's been giving her some fits. When she pulls up to stop somewhere, the car's RPM will dip, almost to the point of dying (it has died a couple times), and then the RPM surges up past idle, then settles in to where it should be. If it was a stick, it wouldn't be a HUGE deal, except that since it's an auto, the RPM surge causes the car to lunge forward, which if she get's stuck in a tight space, she'll hit the car in front of her. She's rebuilt the tranny, but it didn't help. I figured the best place to turn for advice on how to fix it would be you guys It's gradually doing this more and more, it's probably up to doing this lunging thing about 80% of the times she stops. Please help!

 

[streethorse]

Has the IAC ever been changed? If not thats probably it.

 

[wmburns]

How to troubleshoot IAC idle problems

Check out post #3:

http://www.stangnet.com/mustang-forums/810729-starts-but-dies-idle-help.html

Important, check your fuses (all of them).

IMO, If the car is actually lurching forward, this may not be your average run of the mill IAC problem. This may be the automatic transmission lock up torque converter locking up.

One way to rule out a transmission problem is to shift the car into nuetral before coming to a stop. If the idle still surges, this will rule out a transmission problem.

Post up the results of the tests called for in the post and we will go from there.

 

[arcwcb]

I'll be running the tests this next week, but I can rule out the tranny problems because when she pulls in to a parking lot, to keep it from surging forward and hitting a car, she pulls in to a spot and immediately puts it in park and it still has the RPM drop and surge. Thanks for the help, I'll post back with what I find out!