umm one is the receiver in the vehicle on? I don't want to sound demeaning, but I once saw a guy come into the LHS cursing his nephew under for breaking his radio when he disconnected the battery, and the guy didn't check... dude had a $140 spectrum setup in his hand ready to buy when the clerk plugged it in and was like uhh nothings wrong...

Before starting the engine Take the Air filter off the motor, and test to see if the servo that hooks to the motor opens, and closes the carberator properly. It should have a 1mm gap when you aren't touching the throttle trigger.
Should behave like this
http://www.youtube.com/watch?v=qBZbpPpD4ag Then check the brake linkage I'm not sure on that model but most are similar when you press the brake it should push a plate into a disk that is on a drvieshaft. Make sure that is closing all the way sometimes those loosen up.

If all the above is ok then you probably have an airleak... Those are not fun to fix as it can be a pain to locate it.
http://www.youtube.com/watch?v=tZ3WcPoa1DY Personally I'd recommend watching that guys WHOLE series on nitros as its full of excellent info.


One word of advice in the future I'd steer away from used Nitros as pretty much every used nitro I've bought the engine was screwed up, and needed replacing.