you need to head over to the 1/2a (.049) forum,,the engine like most others should be peaked and then backed off a notch or 2, sounds like there is an air leak somewhere or perhaps the glow head is going south or if it sat for 20 years like they often do it needs a thorough cleaning... they need high nitro %25-35 and %20castor for lube,,it might run on %10 cool power but, not well if thats what your trying.......Rog