i have a 1997 chassis that i swapped a 1999 5.4 into and ever since I swapped the engine the truck way over revs and stays up for a period of time before coming back down in RMP in steps 2000-1500-1250-900 or so
and recently with the cold the truck (below zero here in MN) will just bog out before it revs up and die it smells as if it is over fueling quite a bit
So far I have
Cleaned MAF sensor
Checked all coils
Replaced spark plugs
Cleaned IAC
replaced fuel filter
Checked for any vacuum leaks (vacuum gauge)

I cant figure this out for the life of me some input would be greatly appreciated
Nick