He is a problem can anyone solve it - I have an XRAY with a 7 double Reedy Kription, Yokomo Reedy Batteries, Gt7 Speedie, 3PK HRS Radio, Futaba Servo Small one, at half throttle the engine is surging off and on off and on which is causing the car to severly run off the rails it has a mind of it's own. Any comment are muchly appreciated.

it could be a number of different things. my guess is that either the batteries are shot, speedies gone, but it is most likly shotie wireing(or some thing like that)

if it isn't thoes it could be any thing even radio interference.

i think it could also be the placement of all your electronics.
Ive heard that if some things are too close together or others components are touching, it can cause things to go off by themselves.

Done the exercise removed radio gear, reciever, servo ,speed control replaced with a ko servo, ko reciever, LRP sppedie and a mars radio control. To my suprise the stupid thing is still doing it.

All conponent are free of each other and even laid all the new components outside the car and it still does it. I am at a loss.

you could try a power capacitor, that might help you out, search the net for articles about them. hope this helps

check the capacitors on the motor are alright. If they are dead that is probably causing the problem.