ok this is not a chevy but a 98 mustang gt 4.6 sohc, the car will not hold an idle, changed the fuel filter and the spark plugs and the TPS, once you get the car rolling at 1500+ RPm it runs fine but once you let off teh gas the car drops to 400 RPM then dies, any of you guys have any ideas on what this could be?

Chaser
Try cleaning the carbon out of your throttle body and Idle control valve.

You probably need to replace the Idle Control Valve, you can get them at NAPA and other regular parts houses.

It could also be an EGR valve problem. Ford's EGR valves tend to carbon up and stick open, and this will affect the idle also.

so run some carb cleaner through the EGR and IAC? when i took off the IAC had a black powder coating on the inside of the metal wiped it clean but still wont hold idle.

A bad MAF sensor can cause erratic idle or even stalling. Is there no error code set ?

Rob

ok i took off the IAc and cleaned it with carb cleaner and is stil not working, what would make the EGR valve go bad?what does it do to make it die at idle? also the car is throwing no codes.

here's and update i disconected the vacum hose@ the eGr and it idled fine, hooked it back up and still ran fine, but now teh check engine light is on.. :confused: