I have a 1999 gmc yukon got the truck cheap last week $1500.00 had a seriouse miss ,checked compression on #1 cyl was 30 psi,#3 was 180 but misfiring .just replaced the head found out it was cracked. now still have code po303 bank 3 misfire.all new gaskets.thinking maybe an injector but now that i read this possibly going for crank sensor.all new wires dist cap plugs,head .any comments please.help