i have a pan head with mallory unilte billet distributer and this last weekend i reapalced the oil pump and i had the distributor out and i stuck it back in and set it just like the instructions say and i got it set to where it idles great and has a good rev response and at idle it with back fire and shot flames out of both pipes but not at same time and it doesnt do this consistanly its every now and then. i dont know if the timing is off but it dont make sense to me that if its off i would think it would only pop out one pipe. i also thought it could maybe be spark plugs kinda shot and not firing every time. please help i would really appreciate the suggestions.