Pulling my hair out. 5.7 OMC plugs are black and sooty. This just started this season. Boat will run fine at WOT but as soon as I go back to idle it drops cyliders. Replaced coil, points, wires. This happens on cylinders 1,3,7 and 2. The rest of the plugs are fine. Compression was checked and it was good. Motor has about 128 hrs. Is it possible I got some bad plug wires? Boat will start easy and idle fine. I get on plane and it might run well for 1 mile or 5 miles. I cruise at about 2800 rpm. It will not maintain this rpm without fouling. If I run WOT, its fine. Carb was purchased new 2 years ago. I change fuel filter every year. Got ant ideas?
