Have 11 SHO. Have replaced plugs, wires, boots, most coils and all the fuel injectors. I had cate back pressure tested (tech said they weren't bad) and engine smoke tested for vacuum leaks (none found). I recently had a cylinder 3 misfire and changed the coil and plug (the plugs a 2nd time) and yesterday my cel went off when doing.a hard acceleration over 65 (up a hill and passing). After the previous issue with cylinder 3 misfire in addition to that code it had been throwing the p0420 and p0430 codes. Again my cats had been checked and said they weren't blocked or bad. Mainly had done all city driving since the aforementioned plug replacement. Car shifts good, drives good otherwise no issues with acceleration. I've spent thousands trying to get it right. I need some ideas what could be wrong!?! Hopefully I have in right section this time.