I just baught a used rc car (Caster zx) with a .21 Go engine. The first time I fired the engine up it ran good and revved out great but I did not drive the car on the ground. The next day I started the car and drove it and everything worked great (engine temp about 230-240), lots of power! I stopped the engine and refueled, then ran it again and everything was good, but after about one minute the engine died when I opened the throttle. So I leaned the high speed needle and the engine ran great again. A few hours later I took the car out and ran it again and it started and ran good at low speed but died when I opened the throttle, so I leaned it again and it ran good but then was leaned too far and was running hot (over 300). So I stopped it. I checked the fuel system and everything looks good. Later that day I tried retuning the engine but no matter what I did this time the engine stalls when I open the throttle to full. What could be doing this? It ran GREAT the first two times I ran the car, then it changed!
Also the idle has started to quiver a bit now, but not bad though.