Hi. I recently picked up a used Duratrax GP car to fiddle around with, and I'm going to let my girlfriend use it. Now, thing is it was working fine for awhile, but now while the engine is running, I get very bad servo glitching, to the point I can't drive the car. It's the crappy stock RTR radio and reciever. I believe it's a 27mhz AM unit. I've tried insulating all the wires ect. but it is no help. Would getting a cheap 75mhz AM unit help, or should I get an FM unit. Keep in mind, this is just for my girlfriend to bash around with, and I am not spending a great deal of money on it. I have a Cen Matrix Buggy with an MX-3, and I really like it, but I can't get it locally. Thanks guys.

Get her a cheap FM radio and be done with it, then you won't have deal with it any more. E-BAY

Actually an FM radio may not fix the issue. FM will glitch just not as readily as AM.
More than likely what you are experencing is loose metal to metal connectin somewhere. Check all of the screws that screw into metal and tighten/loc-tite them as needed.
Also check the antenna wire attached to the rx to be sure it is not cracked, skined or loose. Many things can cause your symptoms and it's mostly trial and error to fix. Some other things to check are the crystals, the clutch bell, the exhaust and anywhere there is metal touching metal.

Yeah, I've been reading more and more, and the one thing I forgot about the car, is that the throttle linkage is bare metal to the carb and the bare metal spring and the lock nut. Maybe I'll take that bare steel rod, and paint it or something of the like, to see what happens. I know that rattles around like mad.. I'll update if that is indeed the issue. Thanks guys.