RE: Lost my RX, then it came back.
I have just had two R149s returned from Futaba having the same problem. They acted exactly as you described.
Futaba could not identify the problem as they did not act up while they were testing. I hooked three of them up to the same battery pack and sure enough the two identified as bad worked for a while and then died while the good one motored on.
At this point I have little confidence in Futaba service so I am looking for other good receivers.