99 Mustang GT won't stay running...

[jbrown]

its your iac.

 

[Darkhorse845]

IAC and EGR!

 

[joshheat25]

What is an egr and also are the IAC's from a Napa as good quality from ford.

 

[COramprat]

What is an egr and also are the IAC's from a Napa as good quality from ford.

EGR=Exhaust Gas Relief valve. It is the silver or chrome looking disc shaped part on the right side of your plenum. The parts from NAPA are no better or worse than those from Ford...in my opinion. I bought a Rad cap from Ford and I could have gotten the same one they sold me from NAPA for 5 bucks less.

 

[A Mays 49]

My car is doing the same thing. If I am going about 50 and put it in neutral to slow down it will drop RPMs to around 500 then go down to around 300 and sometimes die. I can not get it to reproduce the idle surge unless I am driving so I can not pull off the TPS to see if that is whats wrong. So far I took off my MAC and went to stock with a K&N drop in. Ive checked for leaks over and over. Someone told me my programmer or my throttle body could be messing with my air/fuel mixture really bad, but all symptoms point to a TPS, IAC, or a EGR. Any ideas?

 

[Kane]

Just wanted to say thanks for the help...my 99GT would not stay running unless I kept my foot on the gas. It only did this every once in awhile. Now I know what may be causing the situation. I went out to the garage and used some carb and choke cleaner on the IAC...so far runs fine.