I will try and do my best to explain to you ;
Firstly when you say it cuts out does this mean you cannot get the engine to go at all ?
If this is the case and the engine went on a runaway on full throttle it may have damaged the engine for example snapped the conrod etc...
Try turning the engine over by the flywheel which is situated under the chassis.If you can turn the flywheel with a plug in all the way round without no resisitance then something has gone in the engine;
As for the car going of on full throttle do you have a failsafe fitted at all ?
If not my advice is to buy 1 and get it installed unless you are using 2.4ghz or what is called as specktrum as majority of these already have a fails safe mode fitted;
Could also be that the throttle servo has gone down on you also which would also cause the car to open on full throttle;
The easy way to test this is transfer the throttle servo in to the steering connection on the receiver if there is no steering the servo has gone down on you and a new servo.Also check that the servo gears are in tact and no missing teeth
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