2003 Isuzu Rodeo Question loses gas power while driving

I have a used 2003 rodeo that I just got about three weeks ago and It has already had to be in the shop most of that time. I have replaced the fuel filter and the fuel pump because I was told that was the problem. What happens is I will be driving down the road and the first thing that happens is I will lose power in the gas pedal and then the motor shuts off but the lights and radio remain active. I can start it most of the time after I let it rest for an extended amount of time but not always and the duration I can drive it is not good at all.