My 2006 4.6l auto, has started surging real bad when cold. Its even an effort to hold the car on the brake when in drive. Once the engine is hot it runs perfectly, with no surging at all.
Anyone got any ideas what this could be?
You could always crank it up, then unplug the IAC and see if it settles down at some fixed RPM. If so, then the IAC is probably sticking. If not, the problem is elsewhere. Note that this will throw the CEL, so you will need to be ready to clear that after re-connecting the IAC.