Mike,

I have the EVO trainer and I’m having a very similar problem as you are having. I had a couple of good flights then it started acting as you described. It will idle ok but when I go to full throttle it runs ok for a few seconds then starts to bog down to almost an idle then it might speed back up then down again. I too tried resetting the high and low idle adjustments but could not find a spot where it ran ok. I never had a problem getting it to idle but just could not keep the RPM’s at full throttle. I did notice that I was getting a lot of black stuff coming from the muffler into the fuel tank. I removed the baffle from the muffler and tried a fresh tank of fuel. No more black stuff going into the tank and it would run ok static. I ran 2 tanks of fuel with no problems. It has been to cold and windy here to take it back to the field to see if it does ok in the air. I did the pinch test with it running at full throttle and also held the nose of the plane up 90 degrees and it ran ok. I don’t think one should have to remove the baffle to get this engine to run but that is what worked for me. I would send it in for repair but I can’t find my receipt.

Mike