What would cause car that normally run perfectly suddenly quit any time you apply accelerator

I own this vehicle for the last twenty years and it ran perfectly until recently. I was driving home when I noticed that if I apply acceleration the car would lose power and then stall. Initially I thought it might be the fuel pump but then discovered their was no electrical power getting to the fuel pump. I had a retired auto shop own look at it and he discovered the fuel filter in the fuel injectors were cluttered with contaminates.

Even after he clean injectors filter the car would still idle for a time but then stall. If I tried to drive on level surfaces it would limp along. If I try to climb a moderate incline it would crawl up the incline and then stall. If I left it running in idle it would eventually stall.

Could it be my fuel pump? If not what else would be causing my problem?