Gentlemen, I'm seeking your knowledge in understanding an issue I'm having. After collecting parts to do my own build, I found a good deal on a Turbo swapped vert and pulled the trigger.

It's a ported S5 TII block with a stock UIM and TB that has the secondary plates wired open, Greddy FMIC and a GT35R with a .91 hot side. Microtech with plenty of fuel.

I don't have much seat time in it, but I've taken it out on some 30 degree days and if I get on it in 1st, 2nd, or 3rd gear it takes off on its own, it seems like the throttle cable is stuck but it is not. If I let off when I start to feel it happening, sometimes it will hang out around 5-6k for a few seconds then go to redline, other times it will just go straight to red line and hit the limiter at 7500. The only way to get it to stop is to turn the ignition off.
It is not going lean or breaking up at all, it seems almost like the boost is holding the throttle plates open. This is my first big turbo car and I'm curious about what's going on, and how to stop it.

The car makes 397 who and 295 ft lbs at 18PSI. I can upload a pic of the dyno graph if it will help.

Thank you!

 

Try taking off the Throttle body and cleaning all springs,linkage etc associated with it.
My Car did the same thing and it was the big spring wrapped around the throttle plate shaft that was all gummed up.
It would only do it once in awhile and get you when you slowed down to turn into a driveway or a corner..REV at 6500.