I think car is Overboosting at wot... blinking cel

[blackslc5]

Under full throttle my car shutters like it was overboosting and a blinking cel comes on for 10 sec then goes away. it boosts normally until it hits a little over 21psi then it seems like it shudders. I've been reading up on this and I've learned it could be the n75 valve. I unplugged the electrical part of the valve last night and drove it and only got 7-8 psi. Does that mean the valve could be bad? It's an 01 s4 asp stage 3 ko4's. Any help would be great thx

[Peter1.8t]

Flashing CEL is misfire. Do the usual steps to troubleshoot. If you get confused there's a million threads that can help.

[axnjaksn]

yeap...misfire....check you plugs are gapped correctly.....

[blackslc5]

Thx guys I'll check that tomorrow