Bronco 2 doesn’t like dirt roads

I have a 1987 bronco 2 with a 2.9 liter fuel injected engine. It runs great on the highway but when I drive for 5- 10 minutes on bumpy roads it suddenly losses power and dies. If I wait 15-30 minutes it will restart and run great again as long as I get back to a paved road. I’ve replace the fuel filter and in-line fuel pump. Not sure what to do next. Bought to to 4x4 out in the desert so need it to go slow on bumpy roads.

Thank you.

Check if your battery is secured because it sounds like its jumping up and shorting itself on the hood and the whole truck would just die…then start right up.Also,let it idle and start wiggling the fusible links, just off the solenoid…if the truck dies,you found your problem.

I would suspect a loose electrical connection somewhere too.