Thanks to all, I feel better about using the plug. However; I am chasing a grimlin in that engine. It runs great on the ground and when I hold the plane stait up in the air... no change. It's a strong running engine. It's when I get it off the ground that wierd things happen. somewhere in the flight, it will die. I mean die, no sputtering or warning. It may be 10 minutes into the flight or it might happen on take-off. It is very frustrating, to say the least. Has anyone had this happen, or do you have any advice?