hello I have a 02 Silverado 2500hd 6.0 4x4 and im getting misfires bad, p0300 code and also a egr code p0404 and 02 p0134 codes. I checked the intake gasket for leaks . cleaned maf and throttle body decently. I also pulled a plug but cant tell if its bad or not, cylinder 1 is where the misfiring starts according to scanner. my question is where do I start? buy a egr first? ( cheap china one on there now) or buy a 02 sensor (sensor 1 bank 1 upstream) ? or plugs and wires? any help appreciated . :?
