I did a compression test early on and all cylinders were within 10 pounds of each other. The misfire counts on 5678 were 0-.05. On 1234 they were 0. The best way I could see them was when I was graphing. 1234 were steady and did not waver at all. Flat straight line all the way. 5678 were all over until I brought the rpm's up then they smoothed out too. When I first changed the plugs No. 8 was sooty black and the others were clean. I put the new plugs in and ran the engine for about 10 minutes. I pulled the plugs and No. 8 was covered in soot again. I mention this because the FP regulator sits right next to 8.