My port motor starts off at the dock idling normal. When I put it in gear (most of the time), it starts running a little rough and then will not accept any additional throttle. Even if you move the throttle forward slowing or pump the throttle the engine will not gain RPM, in fact more than likely it will stall. At this point, if you move the throttle back to idle, the engine will keep running. The troubling point is that I can turn the key off and re-start and "sometimes" the engine/throttle will act as a normal engine would....Help!

Check fuel pressure and fuel level.

You need to give more details. We don't even know what motor you are running. Answers will be different whether it's a carb motor, whether it's a Mag EFI motor, or whether it's an EFI/HP motor. All we know is that it is a 502, and we have to assume it's in a 1995 Powerquest, but that's only because of your user profile - this could be an entirely different boat.

This forum is fantastic for getting detailed help, but in order to get it, you have to paint the picture as clearly as possible and leave very little to our imaginations.

MC