I have a 91 gmc with a 79 305 engine and a 4 barrell edelbrock carb. Last night on my way home from work it started cutting out while I was driving. It would idle at stop ok but when i'm going down the road it starts in again. I pushed in clutch and reved the engine a bit while coasting and it would clear up for a little ways then start cutting out again. It has a new distributor and new fuel pump and fairly new plugs and plug wires. I'm thinking that the timing might be off, but i'm not for sure. Any ideas?