Timing issue?

It ain't your timing chain, and not the timing either. Pull some plugs and let them explain it to you.

plugs looked decent they only have a few hrs on them. not fouled out seem like they look ok even for NGK i know i need to use champions but the damn oreily didnt have any and i needed some i will be switching them to champions. i rep lace the edelbrock 1406 600 CFM carb that was on it that was rebuilt by someone. i still have the carb. but the new summit carb 600 cfm electric choke. summit brand was doing the same dang thing the edelbrock was doing. what little vacuum hoses i have are new and not leaking. could the intake manifold gasket be causing this maybe once the engine warms up gasket may leak but runs decent when its cold or just started? gasket looks a little ruff maybe in places it is an edelbrock performer rpm foro a thermo quad but im running new square bore gaskets and a summit one inch carb spacer all new on it. no leaks on that part