iv got a stock 2 barral carb, headers dual, exhaust, and a k&n air filter on my 1977 400. every time i start from a dead stop or ideling along and am hard on the gas it hesitates i let up and then it goes fine. i think my lean mixture screws arent set right does any one know a good starting point for them or any thing else that might cause this?
oh ya iv got a stock eletronic ignition with a single vacume advance

 

My '79 does this when the engine is cold, but not when it is warmed up. Then again, I've never been able to just stomp on the throttle and go either. If it were me, I would check the timing first.

 

Check the accelerater pump.