87 f150 with a efi 300. When I first start it the truck will not idle. I have to rev it up and down for about twenty seconds before it will take idle. It does not matter if it is a cold start or hot, it does it either way. I have two map sensors that I have tried and the result is the same. One appears to be an autozone special that came on the truck, the other is the oe motorcraft that was in the toolbox. The truck also smells like it slightly floods at idle once it does take idle with a random miss here and there. Has new dizzy, cap, rotorbutton, module, coil, wires, and plugs. Could the IAC be causing all of this? The truck has a fast idle of circa 1000 rpm when it first idles on it's own, then settles down to around 750 rpm after smoothing out. The truck has no issues at all when driving, other than trying to die when letting out on the clutch if I don't let it catch it's breath and take idle before taking off. I recently had a crower 19211 cam put into the truck if this could have any barring, however this problem started a day or two prior to the cam install, the problem just seems worse now.

 

In my experience IAC valves get slow to respond as they age. Cleaning them has minimal effect. Also clean the throttle body. There are mixed opinions for cleaning throttle bodies, but I do it.

 

That cam is not helping the issue. The listed LSA is 112 degrees which is below the standard Speed Density friendly 114 degrees.

You have two issues to deal with. Highly suggest you start with a code check (KOEO and CM ).

 

I missed the cam info. Speed Density relies on MAP sensor input to determine air mass into the engine. Since cam changes alter intake manifold vacuum, Speed Density systems are not too tolerant of a cam change. On the positive side, that cam has very short duration numbers so even with an LSA of 112 degrees it's tough to determine if that's contributing to your issues.