Hello all, I'm posting in this (older) thread because I have exactly the same problem with with my SSB SRT6 roadster. I replaced the Crankshaft Position Sensor with a new BOSCH CPS today. No difference. Car runs good until I "get on it" then in the upper RPM range it throws the P0300 code and runs terrible. That is the ONLY code. I can turn off the ignition / restart the car and it runs OK enough to limp home. When I clear the code, it runs good again until I "get on it" again then same code P03000 comes up and it runs like S#*^ again. Recent set of NGK Laser Iridium Plugs and Magnecor KV85 8.5mm wires so I know that's NOT the problem. Are we thinking this is a fuel issue? I have an SL55 fuel pump and the the adjustable fuel pressure regulator. I ran out of time today but will look at the fuel pump area tomorrow and see what the fuel pressure reading shows. Any other ideas are welcome . . . THANKS,