Over the weekend my son was flying his Hotts with a Webra Bully 35 that’s on gas. The engine only has about 6 tanks on it, when it started surging in the air. He landed and I cleaned out the carb but did not find anything. I put the carb back on and it starts but when you go full throttle it surges real bad and will start to run backwards and die??? I thought it was a carb / air leak problem until the engine wanting to run backwards and now I am thinking it may be the Webra ignition giving me a problem?? Anyone have anything like this happen to them???