Hello All, I have a 2009 Tahoe XFE 5.3 LT with the same issues. P0301, P0420, P0430 before installing new AC DELCO plugs and wires with a cylinder 1 coil pack swap- did not follow swap, stayed P0301. Removed coil pack harness from metal bracket (possible grounding/sparking issue? and the P0301 code gone) now P0336 , p0420 andp0430 No Tach, Rough idle, Stabilitrak disabled. Next step is to try Crankshaft Position Sensor. This Engine has been burning oil since day 1, maybe clogged Cats... a/c still ice cold, drives like a caddy, near perfect condition and definitely NOT ready to retire the ol lady.....
