You haven't mentioned what fuel, glow plug, or prop you are running. My TT pro .40 was also a pain until a buddy loaned me his tach, which helped me set it properly. It was very sensitive to the slightest turn of either needle, much more sensitive than any Magnum or O.S. engines I've had. But once we found the sweet spot, it has run like a champ every since. I use 15% Omega fuel and #8 plug in mine. The prop also made some difference. That pro .40 will turn an 11 x 6 as fast as any of my .46 engines, but it loaded it up too much in transition from idle to wot. A 10 x 6 APC seemed to be its favorite prop. I would bet that your .46 would do best with a 10 x 6 or 11 x 6.