Ok so heres the deal. I have a 15 passanger chevy express 3500 with 81656 miles on it it was running great went to xdl nashville tennessee filled up and about ten min later check engine light starts flashing missing like crazy checked code it says p0300 random miss fire changed the plugs wires the fuel filter checked the compression highest was 170lbs lowest was 160lbs also removed the complete fuel rail boy was that a pain let me tell you lol cleaned and inspected everything any ideas this is a natural gas van. ran perfect till then I also sprayed carb spray all over the intake to ruel out a leaking intake any ideas would be great i have to get this thing back on the road thanks :-)

 

ok here is the update checked the compression and here it is #1 160lbs #2 165lbs #3 165lbs #4 166lbs #5165lbs #6 170lbs #7165lbs #8166lbs checked the spark its fine checked the injectors they all check out with a noide light, also replaced the fuel filter removed the fuel rail and compleatly inspected it and cleand it and bod have any ideas im going to go nuts with this thing!!!! please help me asap

 

actual measured fuel pressure? when was last cap/rotor? wires?

 

the fuel press was around 60psi as for the cap and rotor it dosnt have eather its coil on ign ive replaced the pulgs plug wires fuel filter checked the injectors coils intake with carb cleaner no faults also ran it on gm tech 2 th ewierd thing is it wont even pick up some o fthe cilinder purposly unpluged............ update was messing with it again today un pluged the vacume port to the brake boster to creat a vacume leak wierd thing is ever thing actualy started working all cylinders are iring any ideas??? im super stumped now :-(