Originally Posted by BrianBrave
Perhaps there's a facility with a dyno and/or a star diagnostic system in your area.
This way you can run in every gear at several RPM's and look at data before chasing tunes..
Also, have you checked for leaking manifolds?
Can you re-install your factory manifolds to eliminate or reproduce this problem?
I checked for leaking manifolds Brian and the first time they did come loose, then I used some thread locker and they seem to be okay now!