I have a 79 c20,350, qjet, rv cam. Ran great for awhile, still runs great sometimes. My issue is lately when I get on it a little pulling out of a driveway it'll cut out and it'll do it real bad sometimes. It seems to happen more when its hot, it pops sometimes when it happens, carb was rebuilt 6 months ago, timing chain, and distributor were replaced 4 months ago. Timing is fine, disconnected vacuum advance and plugged line, problem didn't seem to be there anymore until I drove 5 miles and parked it for an hour then drove a couple miles again. Gas mileage doesn't seem to be harmed as it still gets 12.5mpg city. What should I be checking for?