I had a similar problem. Under hard driving, high boost, my throttle would stick open. I had to punch it to get it to return. I checked/tried everything. Ended up with a new throttle body. They are not cheap! Its been fine since then. Good luck!!!

 

Well I found the the problem and fixed it!! By the way the butterfly does have a adjustment to it ! Well my problem was when I installed the spring onto the TB I hooked the bottom end correctly but I 4got to slip the tip through the gold slot on the lever! So the spring didn't have enough tension to snap closed when off throttle! Damn stupid mistake but thanx a lot for the help guys.