Cylinder 4 misfire

[Duckie]

I have. A 2012 Yukon Denali Xl I am getting a cylinder 4 misfire and I am stumped replaced the coil wire plug and injector stabi track and traction control lights are on have had a compression check done mechanic said it was good but there was carbon on top of the piston have ran 2 cans of sea foam thew the gas no help I am stumped any ideas?

[CamGTP]

Check for a broken valve spring.

 

The other thing it could be is a bad AFM/DoD lifter as cylinder 4 is a cylinder that shuts off at cruising speeds. The lifter itself could be bad or it wiped the lobe off the camshaft.

[SARNCAN]

I have. A 2012 Yukon Denali Xl I am getting a cylinder 4 misfire and I am stumped replaced the coil wire plug and injector stabi track and traction control lights are on have had a compression check done mechanic said it was good but there was carbon on top of the piston have ran 2 cans of sea foam thew the gas no help I am stumped any ideas?

I guess if all factors are good and replaced new (Coils, wires, spark plugs, injectors, and compression test), then I suggest checking EVAP sensor, oxygen sensors, and fuel pump.