alright, the combo is a 306, slightly ported stock heads, tfs 1 cam, 1.7 rockers, air gap intake and edelbrock 600 carb. the carb has the 8 in/hg step up springs, .101 main jets, 7047 metering rods and the idle mixture screws are about 2 turns out. now my problem....its got a tip in stumble/hesistation. ive tried backing the idle screws out more but it doesnt help. ive changed jets and rods just in case they would help also but nothing. i dont know where to go from here. the car has 16 in/hg for vacuum and idles fine and drives great except for this problem. i guess really the only thing left is a vacuum leak or rebuild the carb or get a new one. someone give me some opinions or advice...thanks fellas