Replaced fuel pump, cuts offs when backing up, no fire power

Had the fuel pump, filter and strainer on my 1994 isuzu rodeo 4cyl 2.6 liter replaced, because it would crank over but not start. Machanic had to tap on gas tank while I turned the switch. Started both times this happened. Decided to have those parts replaced as advised. After replacement of the parts, truck ran fine for a few days, then as I was backing up it cut off and would not start for 15 or 20 minutes. Contacted local auto parts store and explain what was happening, suggested throttle body plate was possibly covered with a carbon build-up, needed to have machanic scrape with a wire brush and spray cleaner in the housing. He says will crank, but not start. Getting fuel but no fire. Been doing some research on how the fuel system works, but have seen previous advice saying ignition module or crank sensor, do you have any suggestions? Check engine light have been popping on and off for the past month or so. Was getting ready to have diagnostic test done, but fuel pump problem happen. Any advice would be appreciated.