My car has 207k on the clock. Maintenance is all up to date. A few months ago I started with a weird issue where I would be at cruising speed 40 to 50 MPH and suddenly the engine started feeling rough and I got a vibration from the engine that would lightly even rattle the dash. I let my foot off the gas and then lightly get the rpms back to speed and back to normal. The problem was pretty rare, but started becoming more and more common about 2 weeks ago.
What I noticed on my aeroforce is that as I am cruising and as the vibration/roughness develops my timing advance drops into the single digits and stays there until i take my foot off the gas. I get 0 degrees of KR throughout this process unless instead of taking my foot off I put my foot down to try to accelerate. Then I get a over 9 degrees of KR. I also have been getting the p0300 code for random misfires. My vacuum lines are all good, played musical coils and ICM is good. The only thing I can imagine is that my fuel pump is dying out as the issue has become more prevalent as of late. I would like to know if any member has had a similar issue or has a better idea of what the issue might be. My worst fear is that I change the fuel pump for an OEM Delco unit and I still get this issue. Please let me know what you guys think.
