i have a much older malibu...it has a 350 in it out of an '87 GMC box van. It has the centerbolt valve covers, and recently i ran the car really hard and the engine started running rough. i thought it would be an easy fix, but i've rebuilt the carb, got the timing just right, checked for jumped time, took valve covers off and everything's good under there, spark plugs and wires are good, fuel is getting into cylinders. new coil too. the only thing i can think of is if there is no power to the coil? what are your thoughts? thanks...