good thought. I found my problem because once it wouldn't start at all. after that happened it started every time. I pushed to find something wrong. Now, I also start my plane with the headsets off and pay close attention to startup and run. I noticed that my plane was starting up but had a different sound after start up. well after not starting at all just cranking I decided to do a mag check right after startup, that's when I found that one module was not firing. after a few second, more than likely after it reached a good rpm like 2000 the offending module started working. At that same time that the module started working of course the engine sounded much better. another good test is to go to one side and than the other when at operating rpm, in other words, do a mag check in flight.