Hello. Own a 1996 Thunderbird 4.6 engine. Problem is noticed on cool/cold days, especially when engine is not at operating temperature. There is a sound resembling a fog horn coming from the engine. The sound stops when I step on the accelerator however. I notice this sound when driving but mainly when at idle. I was told this could be from a faulty IAC/AIC valve?
Could this be a faulty EGR valve as well? Thanks!