97 k1500 P U 5.7 Misfire again!

[jack4321]

1997 k1500 Pickup with a 5.7. It has 93K on it.

 

I have a SES giving me a P0303 code. My reader says its a misfire on cylinder #3. It seems to be running a little ruff as well.

 

I had the same problem 4 months ago with Cylinder #2.

So I did a tune up. Change the plugs, wires, PCV, Rotor cap and rotor, Fuel filter too. The plug on number 2 looked just like the others. On plug 1 and 3 there was a little corrosion. Still had the problem.

 

I then took it to a repair shop and they changed number 2 fuel injecter and the ignition coil. It was runnging smooth for about 7 weeks.

 

Now i have it on cylinder 3. So i changed out the Central SFI Fuel System to MFI (Multiport Flexible Injection) Fuel System.But I'm still getting the same error code on cylinder 3 only.

 

Now what? Could a worn rotor gear cause this just on one cylinder?

[ChevyTech007]

I would bet you have an intake gasket leaking vacuum.

[sclade99]

I second his guess on intake gaskets.

[mmmikkke]

That's about when my '95 K3500 5.7L intake gasket went, right around 100k miles. Had a coolant leak at the back of the manifold. Check for that.