2000 mountaineer engine dies

Was driving the other day when my engine died without warning. Would restart, but only briefly. Next day was fine, mechanics couldn't find anything wrong, but said will happen again. Would appreciate any suggestions.:banghead:

Fuel pump is might be going out. eventually it will leave you stranded. The other possibilty would be a fuel regulator not operating properly.

Was the fuel pump, only took 3 different auto shops.