I have a 2000 5.7L with a 2 bbl holley, and recently when operating near full throttle, I get a popping sound like its backfiring through the carburetor. At the same time the rpms jump up according to the tach (to around 5200) , but the boat speed is not as fast as it should be. Im assuming that the tach gets its signal from the spark triggering device and that is also whats causing some kind of sporatic firing which is also causing the backfiring sound. Distributor,rotor,wires,all look good. Any ideas on what else to look for? Thanks.
