Spektrum DX3S problem?

[Tony Long]

Hi,
I have got a Spektrum DX3S that i use in my DEX210 with a speed passion GT2.0 ESC and a speed passion 8.5T motor. I only race indoors with the car maximum 20m away but at the furthest point the throttle sometimes cuts out. Then last meeting my throttle stuck on for for about 5 seconds sending me straight on then it stopped before my dad (who was luckily marshaling there) turned it off.
I was wondering if anyone else had had similar problems. I have had the transmitter about 10 months but it says i have only had 16 hours of use with it.
Thanks for any help.