I think maybe a vacumn leak or bad solnoid, however, the car boosts fine to 13psi set w/ PFC....but when it hits 6K rpm range, the rev wouldt go up anymore, sounded like hitting a rev limiter. this happens after I dynoed the car and tuning. Everything was fine and it pulled 327 rwhp and 277 tq to redline @ 13psi, after a day of driving, the above symptoms occured. Maybe a bad O2? I changed the plugs, but still no luck. FYI, the car was running really rich prior to tuning, and it went down to 10/1 af before it adjusted the PFC...any advise??

Marco