Thanks guys for all the help and information. I won't be able to get back to the plane for a couple of days due to work, family & weather. I will check and replace extensions, and disconnect the Opto kill switch and see if any of those things help. As far as the spark plug goes, I bought the engine used and am using the plug that was in the engine when I got it, so I am not sure if it is a resistor plug but I will replace it just to be sure. As far as the ignition goes it is one of those that does not have a spark plug boot just a silicone spark plug wire with the Briggs & Stratton type plug connector. The ignition does have a ground wire that is connected to one of the engine mounting bolts so it is grounded in that respect. I did ask about that type of ignition either here on RCU or somewhere else and was told that it would be fine but I still have my doubts. I will be upgrading to the RCXel ignition but that probably won't be till the winter now. At any rate thanks for all the responses and I will post back once I have a chance to work more on this issue and if I find anything. I probably won't fly this plane till I get the new ignition even if I find the problem. I am also planning on changing the receiver just to see if it might be something in there (bad solder joint or something).

Thanks again for all the help.