Motor hasn't been running good. I have replaced plugs, plug wires, coils, tried spraying carb cleaner through carbs, put seafoam in gas tank and I am only getting 2800 rpms at WOT. Just ran it for about 15 min in my driveway, then checked compression and got 120 on all 4 cylinders. Pulled the plugs to look at them and 3 looked the same, a little dirty and fouled. The other was bright and shiny and looked like it had been touched up on a wire wheel. Tried to post pics from phone but it says file is too large. Not very tech savvy. Wondering if carb might be completely blocked or perhaps that cylinder isn't firing? Gonna try spark test next, I guess. Any ideas?