You had 4 with no power - but was running. You took out 2 (increasing compression) and it dies when you give it throttle. Sounds like you are running very lean. Check you're fuel line, it may be letting in air or may be plugging up. Check for debris along the fuel line path. If it looks all clear open up the needle and fatten the mixture some. Did you change to 15% fuel from something else? If you increase the % nitro you have to richen the mix. A very lean engine will run super strong for a few seconds until it gets hot - then the power goes away quickly. If you're not running lean, then you might just need a new glow plug. To check, remove it - go into someplace dark and apply your glow starter. It should glow red from top to bottom (the whole wire) and will likely put off a little smoke as it burns off leftover oil film. What color is the glow plug wire - is it covered in black soot or is it bright/shiney/white? Ideally it should be greyish.