RPMs drops while driving cruising speeds

[tomw]

Quote:We saw that the top left bolt is missing from the ICM. So I'm wondering could this be a grounding issue with the ICM?

I understand that the coil packs must have all their mounting bolts installed to get working grounds for all coils, so maybe the ICM needs its bolts too...
If you look, you can use a scope to check the presence of voltage to 'charge' the coil, and lack thereof that causes it to fire by probing the connectors. If it is an 8-plug head, remember that the intake side plugs do NOT fire all the time, only the exhaust side are full-time firing.
tom

 

[Dprocks100]

I just changed the ICM on my truck the other day and It was also missing the top left bolt. Heard others say the same thing, so I checked for thread holes behind that hole. Mine never had that bolt, just the three. So if you are missing the top left bolt, It probably never had it.