1995ta383

Ok i know this is a GM site but i am going to ask anyway maybe someone can figure out what the ford boys cant. My buddy has an 01 mustang with a built 5.4 out of a lincoln navigator with cobra heads, it has a turbonetics 76mm turbo runnin 17 psi. it makes 700hp and 730ft. lbs. now for some reason when he gets into the higher boost levels 14psi and above the thing breaks up. When you get out of the thorottle it still chugs really bad for a while until it clears up then it runs fine again. With brand new plugs it runs a little better for a pull or two. The car didnt do this for about a month when he first built the car. Any guesses on what this could be.

pwrtrip75

iTrader: (8)

if it runs good for a bit after you change the plugs then i'd say thats what was bad. Id question the tune, maybe its diving a bit on the rich side somewhere?