Computer telling IAC to go full throttle?

[XavB]

I've been having problems with my car starting and it surging pretty bad when i go from reverse to drive or when turning the A/C off and then on. The mechanics at ford couldn't recreate it enough to figure out what was wrong so they put a flight recorder in my car. I got it back to them on Friday and they are telling me that the computer for some reason is telling the computer to go full throttle. Does anybody got any idea what they are talking about or why it might be doing this? Any ideas how they might tell me they are going to fix this? I'm going back tomorrow and what to have some kind of idea of what they are talking about so they don't try to burn me. They keep saying the TSP and IAC and all of the other sensors are fine so I don't have any idea what is wrong. Anybody?

[mlambrecht82]

They mean that the Idle Air Control valve (IAC) is opening up too much, which will raise your idle speed. The computer controls the IAC to maintain a certain idle. When you turn on your A/C or headlights, or something that would put a load on your engine; the computer tells the IAC to open up to compensate for it.
You may have a loose connection to the IAC or something like that which may cause it to surge. If they took the IAC out and tested it and said it was fine, then it is either the wiring/connection, or the computer has some bad programing.