Been having trouble with motor not reaching max speed. Usually at 5900 RPMs i will be running 64-65. Now motor will get up on plane good and run good up to around 50-55 MPH and just stay there. It is inconsistent but usually after 5 min or so it will "pick up" and run wide open. Some times it will never pick up. I have had the low pressure pumps replaced, soaked and cleaned 02 sensor, brand new set of NGK plugs and cleaned the filter in the VST. Tired of throwing money at it with no solution. Any suggestions are appreciated.