P0300 GMC code is showing

Question

Hello I have a 2002 yukon denali xl 6.0. I was on the freeway and all of a sudden the truck cut off. Once I got to the shoulder it started but was shaking badly. After I got it home I changed the fuel filter, spark plugs, all 8 coil packs, and even replaced all of my injectors. The truck still won't run correctly. Maf sensor ok. Where do I go next cause it was running fine than all of a sudden really bad. I used the code reader and all it still say is random misfire. What direction do I need to go next.

Answer 1

P0300 Random misfire

There are 2 area that you may want to look in to, there the intake manifold gasket that tends to deteriate which tends to allow unmeter air into the intake manifold which will cause a P0300. This type of P0300 will not cause the engine to shut off especially on the freeway. it worth looking into . another cause which is the fuel pressure regulator pull the vacuum hose off the regulator if fuel is seeping out you would replace the fuel pressure regulator.