Got out to the hanger yesterday. Pulled all the plugs and checked gap -all looked good. Put all back together and made sure to really push on the plug wires. One plug appeared to have a far cleaner look than the rest - so maybe wasn't firing as well? That said my test run went much better. Although, when switching off lanes the rpm actually increased by about 120 rpm - not decrease. I've never seen that before. Switching both lanes back on it would revert to the exact starting rpm. A difference in rise? between each was 20rpm.