XRAY - Model racing cars

I recently purchased the M18T from the gentleman who won it at the recent International Indoor Carpet Championships in Vegas. Who every assembled it from rc america or Xray did a awsome job. Handles awsome and drives straight as an arrow. Here is my problem. It has The Xray Power pack. 300 motor ESC Airtronics Blazer controler and reciever. AM radio. If you turn the rx on before the tx, you sit the car down to go. The throttle controls are reversed. To reset you shut it down and turn it on the proper way. But sometimes when I am running it it comes to a stop then wont go. Few seconds go by. Then the throttle controls are reversed. Then I have to shut it down and then turn it on again. What gives? I would hate to have to scrap this setup for Novak Spy and Spektrum so I would use my M11. Thanks again for your help!