I own a 98' F150 XLT with a 4.6L v8 engine. i had the codes read and it came up with a misfire on cylinder 2 which i've fixed; I've had plugs, coils both replaced. but it also says it could be a vacuum leak. But i also have another code for EGR system fault. and i also have a code for lean system in bank 2, could these all be linked?