1999 mustang gt has ported and polished pi heads and ce262 cams, shortys and H pipe. I just bought the car and it had a missfire, rough idle and p0174 code which i believe is system too lean bank two. Replaced plugs, tps, iac, and got rid of the missfire code however it still has a missfire below 2000 rpm and a rough idle stalling occasionally. I have checked all vaccum lines including the ones going into the fender well, replaced plugs, maf looks to be spotless so i didn't clean it. There is an exhaust leak on the driver side header to H pipe flange that i am going to have to get fixed but i don't believe that to be my troubles if so i would think it would show a code for bank 1.The cops that are on it now are brand new although idk the brand they're red which made me think msd but they zero identufication on them. Could it be an injector or a COP, also thinking of replacing all injector and cop connectors incase that's my trouble there are a few clips broken. Any help would be appreciated.