Drove to Heathrow and back this morning, driving there had no problems whatsoever, how ever on the way back just after rejoining the m4 my car lost all acceleration and power. It was as if something had cut out. I was able to drive home but couldn't pull away, from 4th gear onwards it wouldn't rev above 2800rpm, when I got home I switched off the ignition (waited until I got home as I was worried I wouldn't make it back otherwise) and switched it back on I had all power and was able to accelerate as normal. Slightly worried this may happen again.
Any suggestions on what it may be?