I have a 79 reinell 19' with a 5.7l chevy 4 barrel holley 650. Been running great, last time out it developed a problem. Fires up idles great, when i get between 1-2k rpm under load it's surging like I'm bouncing the throttle ,but i'm not. at 2k rpm it smooths out and runs great again. Any ideas, I'm thinking power valve in the carb. Thanks, Mark.