TRUCK SHAKING AFTER TURNING OFF

[Mr. Van Regenmorter]

Ive got an 08 burb, LTZ, 5.3 4x4. When I go to turn it off, its been shaking. Kind of reminds me of an old 350 that's out of time. Ive replaced all plugs and wires and did the intake gasket, just in case there were any leaks. No cel. It did recently start doing this maybe a month or so ago.. I'm going on a 2k mile road trip in about 2 weeks and want to make sure I'm good before I go. TIA

[CamGTP]

So it's like dieseling or running on after the key is off?

[Mr. Van Regenmorter]

Slightly, it'll shake for about 1-3 seconds then turn off.

[Mike GMC]

You might try some good fuel system cleaner lime BG44K and we I that will clean up your combustion chambers.  It sounds like you may have significant carbon build up.  You might also try a tank of premium fuel and see if stops.