Hey Scotty! I've been a fan of yours for some time now. I love the content you make on your youtube channel. I can't resolve my issue for the life of me. Make a long story short, I recently bought a 2003 Chevrolet Silverado 1500 HD. I brought her to a reputable mechanic(or so I thought). I later found out that the mechanic is just a great parts changer he doesn't know much about diagnosing such as yourself. He charged me $400 for a fuel induction, he cleaned out her throttle body and put on a new mass airflow sensor and I'm still stuck with the rough idle and I asked him what could we do next since I've already paid him $400...well now I'm here begging for your help. He's not even close to being on your level of expertise. The engine is a 6.0l Vortec. Please help 🙂
A bad catalytic converter or O2 sensor will cause a rough idle, maybe check for vacuum leaks while you at it? It also could be the Idle Air Control on the passenger side of the TB, those are some of the few things you should check first.
