I am rather new to flying (4 months) and I have a super stick 40 with an OS 46 AX installed. The OS was also used on my previous trainer. I had no problem with the motor until three flights back. The engine just lost rpm after an inverted flight. It didn't die at first but after working the throttle to regain rpm I eventually had my very first dead stick and crashed my plane. After a few days of repairs I took her up again, and again the engine just suddenly lost rpm. This time I landed with no damage. I might just add that the engine runs real good on the ground. I adjusted the low and high needles by the book, leak tested the tank, replaced the brass pipes in the tank, cleaned the carb etc. but nothing helped. The engine still starts good, picks up rpm but then takes a second or two to peak. I asked all the gurus at our club who all tried to dial the engine but there is no progress. What can I do??? One guy suggested that my fuel may have collected moisture (due to our summer rainy season). I must admit that the fuel I have is less than fresh. It is about 5 weeks old. I also fly only 20% oil with no nitro.

I am really lost here. Please help!