Quote Originally Posted by 632 Regal View Post
Swapped everything from Nikky before I sold her. MAf computer boxes etc. Even the 3:64 rear gears. Nothing changed. No backfires, can tell them when it gets cold if it's the intake gaskets. plugs look good, non-gapable type. Been through it all, not an intake leak issue. The motor pulls a bit harder than my sons 328 at the time. However this current engine as I mentionsed does not pull until 4000 rpms (4200) and then it is weaker than Nikka. Engine should start to pull before 4K in my opinion. Engine has all the 3.0 garb, intake the small one, throttle body the small one, intake and even the airbox intake is the small 3.0 same as Nikka.
Also considered the oxy sensor and the FPR? And btw 'non-gappable' are all gappable if you try. I usually compare the old to a new one out of the box before doing anything- they do wear and sometimes people fiddle with them without knowing what they're doing. I've seen some that have been dropped on one side- and it doesn't show unless you check them very carefully, esp if you wear glasses- though I wouldn't have said that before I had to get a pair for seeing things near me more clearly, LOL...

There is a solution somewhere. You must not expect obvious symptoms, codes thrown and so on for something that is causing power loss at high rpm.