Engine idle surges up and down when stopping at lights

[Larrysr1957]

I have a 97 ford 460 that has an idle surge and sometimes stalls when stoppingat traffic signals or signs. The mechanics has replaced the throttle positioning sensor and the idle air control and cleaned the fuel system. The idle rpm's still surges.there are no codes. Any help is appreciated

[opnspaces]

Does the surge happen more often when coming off the highway to a stop?
I have seen issues with cars in the past where the EGR valve sticks partially open and the engine runs rough or stalls after cruising down the highway.

If your engine has an EGR valve and if it's accessible try this. When you come to a stop and the surge is happening, pop the hood and tap on the top of the EGR valve with something heavy like a small hammer or a big wrench. If the there is no change then the EGR is probably not at fault. But if the surge stops then get the EGR valve looked at or replaced.

[Larrysr1957]

Fuel pressure has been check and is good. IAC has been replaced. It happens with the a/c on and off. The surge occurs a lot engine stalls occasionally
Sorry to answer all questions at once but I don't know how to answer questions individually

[ScottG]

IAC valve.

[Krusty]

Does the surge occur all the time at idle, or just occasionally? Otherwise does it run normally? Does it matter if the air conditioning is turned on or off?

[Krusty]

Heisenberg wrote:
The item on the end of the fuel rail. The name escapes me. Help me folks.

Fuel pressure regulator?

[Heisenberg]

The item on the end of the fuel rail. The name escapes me. Help me folks.