im not sure what happens but just started doing this recently. whenver i do a WOT pull on 5th gear ONLY, car studders like hitting a brick wall, psi jumps up to 34psi, my psi is set to 24. i was thinking maybe a fuel cut but i have upgraded to walbro 255 long time ago. it started doing this..any ideas?

Sounds like it may be boost creep.

What modifications do you have? (O2 housing and boost controller?)

might be due to the colder weather

Why the hell are you doing 5th gear pulls? Thats a great way to mess yor engine up

Boost cut is kicking in to protect your engine from the overboost, that's the brick wall you're feeling. Boost cut isn't the problem, boosting to 34psi in the first place is.

Saw a thread similar to this not so long ago. Fuel cut won't be triggered by lack/excess of fuel by the fuel pump. It's triggered when your boost goes over a preset limit for over a preset amount of time. (ie if boost stays over 25 psi for longer than 1 second).

It looks like your boost is spiking and fuel cut is kicking in to stop you leaning out and doing serious damage. The guy in the last thread I saw pulled a P0234 code which is wastegate system fault. I would start with the wastegate.

Something's definitely up if you're going 10PSI higher than you think you should be. That's what you should be worrying about, not the other things that go wrong when it happens

I had the same thing and just adjusted the wastegate duty cycle for the colder winters and fixed it perfectly

its tuned for 24psi but just started doing this when the weather got cold in 5th gear only..i have fp green with all supporting mods, i try to turn down to 21 psi (wastegate pressure) using greddy ebc but still same thing...last time it did that was due to the vacumm hose to wastegate came off but i checked it too