1976 chevy 350. Jacuzzi jet.  A year and a half rebuilt of the boat (not the motor..$$) So I don't know how it ran before with last owner. Motor runs fine out of water of course. Took it to Elsinore today, wouldn't go fast enough to get on plane. At about 1/2 throttle it would start to bog, any more than that it would backfire then start to die but continued to run. ??

Can it it be a timing problem? Hopefully not a pump issue.

Thanks

Been "sitting" for a couple years, howver, it has been started an ran every few days for the last couple months. It has a quadrajet on it now. the gas is recent and the fuel filter is new.