i have a 87 formula with a 75 chevy 350 4 bolt main 300 hp turbofire. recently i have added edelbrock intake,600 carb and accel distributerand k&n air filter(14x3).the problem is that no two days are the same in performance.the first three days on intake install were the bestand no matter what i do cant get it back.tried timing,differant carb,coil,wires,and plugs.still has old truck exhaust manifolds.