P0300 Chevrolet -

Question

Changed plugs and still getting random misfire. It began with a #2 cylinder misfire theme changed to random after plugs were changed.
Was driving and engine sound changed and check engine light began flashing.
After plugs were changed (they were all needing changing. The gaps were around .080. Changed #2 coil, no help. Almost feels like water in the system, but it was running too good for that.

Also it idles very rough, but will run much better at a higher rpm.

This all came on in an instant; which rules out a bunch of stuff all happening suddenly at one instant.

Answer 1

P0300 Random misfire

The sparkplg gap if you use AC delco is suppose to be a (.040 in). Check the fuel pressure regulator this has a tendency to leak fuel into the intak manifold, with the engine running remove the vacuum hose to the fuel pressure regulator if fuel comes out replace the pressure regulator.It is also recommended you do a throttle body cleaning and a MAF sensor cleaning.