Fulliautomatix:
I'm using one keyfob to control two motors...
Sensitivity of those (433MHz) receivers is decreased with noise sources nearby.
Are there suppressor capacitors on the motor terminals.
Did you power the receiver from a "clean" source (not from the motor supply).
You can try if moving/pulling the receiver aerial coil out a bit helps.
Otherwise a home-made sleeve aerial might be the only option.
Leo..