I just got home from a fly and drive trip, I bought a 1993 NHP Ramcharger with a 5.9/518 combo in Reno, flew out late Wednesday night with my wife and daughter. The seller met me at the airport and I was a bit worried at first as it was running on 7 cylinders, he had mentioned a rough idle, but it was much worse than expected. I said the hell with it pressed on Thursday AM after buying some
Oil and antifreeze for the trip. The engine smoothed out at about 65 MPH on the highway so it seemed ok for the trip. Eventually Ininched it up to 80 MPH and made it to SLC Ut Thursday night. Friday we moved on to a detour in Ft Collins and during a gas stop After running 85-90 MPH across Wyoming she was running great, smooth idle and excellent power, woo hoo it fixed itself! Ran it up to 100 MPH and all was good in the world, unfortunately by the time I got to Ft Collins the miss had returned, but it was still smooth at 80 MPH so after partying for St Patty’s day we left late in the afternoon and ran to Council Bluffs Is, once again alternating running smooth or on 7 cylinders on various stops. Made it home this afternoon with no other issues besides the misfire. Averaged 13.5 MPG over the near 2000 miles and didn’t burn a drop of oil. (Rules out a bad plenum gasket, which is what I thought the problem might be.) Going to change the plugs tomorrow to see if it’s something that simple.