Hans, pull your injectors and soak them in injector cleaner overnight. Replace the O-rings when you reinstall them. It's good maintenance.

Or get them down here to be cleaned and matched if it's in the budget. It can rule them out, and you have another car to drive for the week they'll be gone.

What are your TPS voltages at idle and WOT?

wow, that is really bad...i think my LN3 accelerates faster, maybe not, but it feels like it..yeah i would say clean the injectors, change the furl filter, it might be starving, and other than that...i dunno. Hope it all works out.

Not to be a PITA here..

We seem to be trying to diagnose issues on this car for performance or speed a lot lately, we know you have cracked exhaust manifollds that are most likely giving you a ton of KR.

I would like to suggest the known issues be fixed and then diagnose from there. Meanwhile we'll be spinning our wheels.

TPS tests properly, replacing doesn't make $$ sense, why replace known good parts?
Coils test good
Plugs are new
Wires are new
Maf should be clean
TB should be clean

Honestly...the largest issue here that I can see causing a peformance problem is KR from cracked exhaust manifolds.

I agree. We need to rule out as many FREE or very cheap fixes/items, and take care of all known items first.

Each one is going to give you a little more. Injectors won't buy you jack if you have cracked EM's. Tackle that first, and while they're off the car, take care of other issues. Or send your injectors out at the same time to make use of the time the car is down anyway.

Would a restrictive cat do this to him? Would this show up on his boost gage as overboost? The one vac line that I came across that really looked bad was the one that connected to the trans modulator. Another one to check would be the line to the FPR.

Also, what about a compression check?