Logan Castlen

I recently bought a 2000 Mustang Gt. It has a bunch of aftermarket work done to it already. Stage 2 clutch, stage 3 cams, x pipes to MagnaFlow, cold air intake, upper and lower intake plenum, 410 gears. Now the car starts and idles fine. However a few minutes into idling it will start to idle rough and bog down then Rev and bog down then die or continue to do the reving. Also as I drive it would do the same thing as it came back to idle. I've replaced the tps sensor already and I've reset the computer. The issue is still happening. Now mind you its only as the car warms up. Once the temperature gauge shows its at temp the issue goes away and it idles fine. Idk where to go from here and I'm a bit lost as to what to do for this issue.

dawson1112

Pull the idle air control and use some break cleaner to shoot down it it and clean the valve. Some times a new IAC is the only route. They build up carbon and gunk in there and cause it to hunt idle. At this time you can also inspect the throttle body and clean it out. Insure the idle set screw has not back out from the throttle blade. Do a search on how to reset or relearn base idle.

Also pull the MAF and get you some MAF cleaner spray and carefully spray the 2 sensor wires in side the collection sampler.

Hunt down any vacuum leaks you may have.

Logan Castlen

I had intended to take off the IAC and Maf today to clean them to see if that would solve it. I had done some research that told me to do what you instructed. Hopefully I don't have to replace the IAC. Anyhow as far as vacuum leaks, I had a mechanic take a look at the motor and such and he told me he didn't hear or see any vacuum leaks.

WJL

first is it throwing any codes?, with Stage three cams the car has to have a custom tune and this could be an issue and may need to go back to the tuner (what's on and what is turned off in the ecu).

Sometimes believe it or not a malfunctioning engine coolant temperature sensor (ECT) can cause engine management issues.

you can check it if you have a meter check the resistance value of the ECT while it is cold 50 to 65 degree F resistance should be 58, 750 to 40,500 Ohms

Start the car let it warm up check resistance again 180 to 220 degree F resistance should be somewhere between 3,600 to 1, 840 Ohms

I only bring this up because you had mentined it fine once it warms up, good luck