Hi i just started with my first 350, its mildly built 86, has holley 4bbl double pumper shorty headers dual 3" pipes edelbrock intake nothing much yet. Its inside a 1990 SWB 1500 it was running fine till i started hearing a ticking and found out it was a piece of the header gasket blew out and after i fixed that it started missing when in drive but in park or neutral it smooths out tryed messing with the time and the only way it smooths out is if i put it all the way into advanced passed 12 and if i try and go any lower it starts to miss real bad tryed new plugs new dist. cap and rotor..