RedAndWhiteStang

I just recently put a 5.0 out of a 90 Mark VII into my 92 2.3 Mustang. The 5.0 run perfect like it should while it was in the Mark VII with no idle surge. Now that its in my mustang it does it some times...The first vid below (ignore my oil pressure gauge I was gonna post that in another thread about my pressure sender but I put in a new one and it works as it should now, my car just happen to do some idle surging while I was recording the gauges..) at around 30+seconds youll start to here it idle up and down and the batt gauge moves with it. But when I first crunk it up it didnt rev high or anything (it does rev high when I crank it at one point in the 2nd vid) itll only do it some time. It likes to do it if I get on it then come to a stop kind of quick... but if i just touch the gas slightly itll stop usually. What you guys think the prob is?

Project 5.GO!

Clean the IAC. The IAC is the go-to part for idle surging. I have to clean mine out every couple months.