GMC Repair: 1997 gmc yukon 4wd 5.7L, intake manifold gasket, valve piston

Question
I have a misfire on cylinder #6.I've had a full tune-up spark plugs,wires,distributor cap,rotor button,fuel filter,#6 fuel injector replaced.The check engine light still flashes and my truck still shakes. What other options do I have?

Answer
Hi
if you have done all you listed, the next area to look at will be Engine Mechanical.
Preform an engine compression test.
preforme a running compression test.
Could be a valve, piston, cam lobe, etc....
Also preform a cooling system test on the cooling system, pressure up the radiator with pressure tester and see if it holds proper pressure.
If not I would also suspect possible lower intake manifold gasket failure.
JUst advice from experience.
Hope this helps
Good Luck
Pawl