I've got a 2000 chevy z71 5.3 with 150,000 miles on it. The problem I'm having is while the truck is at a Idole it has a misfire. Doesn't skip while going down the road. The misfire is bouncing all over the place. Iput new plugs, wires . fuel filter, fuel pump, change te FPR coils seem to be ok. Ac plugs and wires. also change the intake gasket and still haven't solve the problem. I've have no sign of a blown head gasket. I'm running out of options. The cads doesnt seem to be bad. I've not change the o2 sensor. Cleaned the egr valve Can someone help me with this please?

 

what do you mean the misfire is bouncing? have you had different codes?

 

What is the P code?

 

well it was only showing a misfire on 7 and 8 it and now it has moved to 1,3 and 5. The code just shows a random misfire. It seems to get worse when it gets warmer.

 

I had an egr code but after cleaning it went away. only showing a misfire code

 

OK, so your getting a P0300 code (random Misfire) is that correct. And no other codes set, right.

 

One other thing, Do you remember what the egr code was? A defective egr valve would leak exhaust gas into the intake manifold. Also a vacuum leak at the intake manifold or throttle body.

 

No I don't remember

 

OK, so you cleaned the EGR valve, did you also clean the intake port to the EGR valve?