I do have a washer for the plug. I replaced the plug when I initially purchased the engine with an NGK... I believe it is the BPM6RF. Motor has run great right out of the box since new. Great idle and transition with very few adjustments.... up until the plug came loose. Now it is shutting off at anything above half throttle. I am going to try removing the H needle and cleaning it out. I do have a felt clunk in the tank, and my fuel jug is filtered as well. It may be that the ignition fried when the plug came loose. This is only my second gas engine, so I am in uncharted territory here. Thanks for all of the replies in helping me to troubleshoot!
Rob