1996 Chevy Nova loses power and engine cuts off

After driving 30/35 miles motor loses power and then it stops running---after a minute or two can restart and go another 30/35 and same problem occurs--have had the following parts relpaced, oxgen senor right and left, fuel pump, inline fuel filter, engine tune-up(plugs, wires, air filter), power steer housing and serpretine belt, fuel injector good, battery cables---I'm at $4500.00 in repairs so far---don, t tell me am crazy I'm way ahead of youany suggests would be great appreciated.---PS check engine light still comes on and codes say replace oxgen senors---thanks james