I know you said you double checked your ignition but, are you sure one of your wires ( 1 or 6 ) isnt going between the exhaust man? This happend to me. I paid $80 for MSD's and thought Ild be ok with 3/8" hose around them but when the computer would try to advance timing it just wasnt happening. I got a real bad sputter, NO tach flutter. I had my hood off til I could get it runnin right and FP would jump back and fourth between 38 and 48 really fast. :2cents:
Mike