Ok ive been have a little problem with my car thats got worse over the course of about 4 weeks. First it would break-up, or cut-out at higher rpms and each time it would cut out the cel would flash for a light a second. From there it just got worse to were in any gear excect first, that after 4500 rpms it would just start to backfire and just fall dead on it face. For a while i didnt evan have to be boosting and it would just kind of sputter and cutout, until it was fully warmed up. Wierd thing is i boost fine all the way to 13 in any gear, its just when the second turbo comes on. I tried to pull some codes, but i get nothing. Also my plugs are kind of bad, so i have a set on the way, but i checked all the vac lines, map sensor, and just about everything i could think of. So i narrowed it down to the plugs but they wont be in till tues. Any suggestions on wut i should look at for the time being.

Mods are dp,smic,intake,hi flowcat, exhaust, and fluidyn rad.

 

Try resetting your ecu, that helped me one time. But i'm guessing you have a boost gauge by telling us you can push 13psi before 4500rpm so whats you boost gauge saying after 4500?

 

it just goes back to 0 and the car starts bucking.