2002 Renault Scenic Sudden loss of power

Hi

Could anyone help me, I have a 2002 Scenic RX4 & it has this intermittent problem where I will be driving along and with no warning the car will suddenly lose power. The taco slowly drops & no lights come on the dash. The engine does not actually cut out. I can sit on the side of the road & wait & the engine will come back up again & drive normally.
I thought it only happened when it was hot weather however it happened on a relatively mild day the other day. The auto electrician thinks I might need a new fuel pump but it is just a guess - as of course the problem only happens when I am driving.

Any guidance would be appreciated.