ok well i have just redone my engine and had this problem with 4and 7 fouling out. I have changed everything on this car except the main harness does anybody think that the problem would be in the main harness its out of a 92 and is in a 93 . i have checked the fire with a tester and it is showing that 4,7 have a really weak spark at idle but when i give it gas the spark responds the same as the others do,would a msd box fix this ? the car sputters pretty bad somtimes while driving but feels ok at wot and even somtimes is smooth as can be under normal driveing. somebody help .