So I just picked up a new IACV. $50. I'll put that on maybe later today.

The other question is back to PCVs. I found PCVs in each valve cover. The problem is, one is smaller and connects to the throttle body (bad...we already identified that was bad), and the other one is bigger and connects to intake plenum just downstream from the air filter (that's fine, yes?)

I think I need to cap that port on the throttle body and 'T' the smaller PCV in with the hose running to the intake plenum from the bigger PCV. Is it okay that the PCVs are different sizes between the two cylinder banks?

Have mercy on me...I sort of adopted this Mustang. Its my girlfriend's, and her ex was, uh...not the most detail-oriented sorta fella. Trying to make this pony right.

A youtube is worth a million words. If what I said above doesn't make sense then view this video here:

 

ok, the left valve cover should not have a pcv valve in it, it should have a fitting and connect like you have, if you look closer at it you will most likely find that its not a valve at all, unless someone put one there incorrectly, this allows fresh air from the filter to enter the crankcase, the rh valve cover should have the pcv valve in it and it should connect to the port u have there on your upper plenum, this allows the engine to draw the air from the crankcase into the intake, because its supercharged the pcv valve needs to be working correctly, because under vacuum it opens to allow flow, and under boost it closes to prevent boost from entering the crankcase. if in doubt of the valve, replace it. i was looking at your other pics and didnt realize what u had going on there, the video helped greatly,

 

Excellent, excellent, excellent. Thank you so much. Makes sense.

It looks like the PCV has been popped out of the right valve cover. :[

I also found a vacuum line disconnected that goes from the intake plenum to some modules (one on each cylinder bank) that may be fuel rail related? Or ignition related? Not sure. Gonna look closer. But the point is it was disconnected and now it's not.

Gonna get the new IACV mounted up and ensure all lines are connected, then take it back to the last shop that did a dyno tune and tweaked the MAFterburner and have them do it again.