2004 6.0 Misfire with good spark, fuel and compression plus new everything !!!

[GreekBoy]

Hi,

I have had this misfire which has burned up two cats now, with the most recent during diagnostics only. 

I have new wires, plugs, injectors, fuel pump and coil on cylinder #4 which has the most misfires with #6 right behind. Truck feels like dead miss on two cylinders too.

 

P0300 only code. Any help would be very appreciated. 

[richard wysong]

where it is 2 adjacent cylinders you probably have a blown head gasket between the 2 cylinders but do a compression test and a cylinder leak test on those 2 cylinders before tearing into it. Could be bent pushrods, broken valve springs etc as well

[Dylan Happel]

I'm going through this exact same thing.

Everything is known good. injectors, coils, wires, plugs, compression, fuel pressure, injector pulse, injector balance test all dropped them the same amount. 

Throttle body is clean, MAF is clean, intake tube is clean.

misfire data doesn't show up all the time but when it did show it said 5,7 and 4,6 but 4 and 6 were very low misfire numbers.

I'm completely lost. I've been talking it over with a GM Master Tech and he's semi-stumped also.