Can you just check a few things first:
1. fully charge your lipo battery,
2. Make sure the battery in your remote is in good condition,
3. Make sure the antenna wire is away from all spinning items (e.g. motor & belt)
4. Because your remote is AM signal, try test the car in an open area (e.g. foot ball court)
posibly in day time before the lights are on (the lights can interfere your radio too)
5. Try not to move your car too far away from yourself (the remote).