I just replaced the IAC this morning but when you hit the accelerator pedal quickly there is a second or so hesitation before it responds and it almost sounds like it may quit. It had been stalling when you attempted to accelerate quickly. We had already tried cleaning the IAC once and it helped for a month. The idle problem seems better but it still has the hesitation and no codes. Any suggestions would be appreciated greatly.

 

Guess you already changed the fuel and air filters, PCV valve, plugs, wires, etc. Have you checked the fuel pressure? Might run some injector cleaner through it. You could also check the TPS with a meter to be sure there's not a dead spot in it.

 

I changed all of those when I got it in jan. I will check the tps and see , also will try the injector cleaner. It had not been maintaned exactly as it should have been before I bought it.

 

Try checking the TPS. It could also be the fuel pressure regulator.

Here's a tip. To make the engine run even better, get a can of SeaFoam from Napa or Carquest. Let the engine suck about 1/2 of the can in the engine from the PCV. Turn the engine off for about 10 minutes while the chemical breaks down the crap inside the engine. Turn the engine on and enjoy the smoke show. It's awesome!! You should get at least and extra 3 mpg.

Use the remaining can of SeaFoam and pour it in the gas tank. It'll clean the injectors.

 

I tried the seafoam today. You were right, it was a big smoke show. So far it seems to have helped. I am thinking of putting some in gas tank of my expedition also.