SO I have a 2008 Tahoe that is having an engine problem. It started with a rough idle that has progressively gotten worse.

I have pulled the codes and the first one was a cylinder 7 misfire. I replace all of the plugs with OE and it went away for a little bit. I then got an o2 sensor code and replaced the o2 sensor. This cleared up that code. Then I got a crankshaft position sensor code and replace the sensor and it went away. Then the cylinder 7 misfire came back. I replaced the coil pack, wire, and plug but still misfiring.

I did some research and it seems that this is a common problem so I have tried all of the things they have suggested, wires, plug, coil pack, fuel injector, throttle body and mass air flow sensor. It seems that every part that I replace makes the idle worse. When I put the throttle body on and went through the re-learn process it would idle at 3000 rpm and not change, so I put the old throttle body back on and idle is at 500ish and still rough. I really don't know what to do from here and hoping one of you smart guys can help. I really don't want to have to take it in to the dealer. Thanks, sorry for the long post.