'93 APV loosing power while driving

I have a '93 Lumina APV, have had it since new. My van runs and starts just fine, but while driving it longer distance than just in town, My van will just loose all of its power. Example driving down highway at 65mph van looses power instantly and max speed is around 35 to 40mph unless going down hill. The SES light does come on and stays on until you shut the van off. took to a service center and they stated that no codes are showing up. Any help would be appriciated. 3.1 motor.

Please, consult a dictionary on differences of "loose" and "lose" for clarity sake.

Check fuel pump pressure.