I think this is related to the spark plugs, so I am going to order some new plugs and wires (NGK and MSD wires?). Car has 16k on the plugs/wires. I hate to take it to a shop to have it fixed as thats a day or 2 of them dicking with the car and who knows what they will say. It started to do it last week . Car runs fine when the rpm's are over 3k. I know the car did this before below 3k when in 5th gear it would shoot to 18psi and cut (overboost), But it seems to pop and buck around 12psi and then it comes back alive and goes to about 15psi.. any idea's? No codes, running 93oct all the time.