1986 Ford Ranger vehicle looses power on hills

Have you made sure the timing is right?
If your timing belt got loose, it may have jumped a notch which would result in poor performance.
I don't think you've checked that yet.

I'm trying to think of something else beside your fuel pumps. So here are a few more ideas:
MAF (dirty sensor) and high exhaust back pressure (let's see if we're not dealing with a plugged converter or something).
Finally, check your intake vacuum; a low reading could mean you have a leak or a bad timing, a reading that keeps dropping would indicate a clogged exhaust, and an oscillating reading indicates a leaky valve or worn valve guides that leak vacuum (you said your compression is good so it's probably not the problem, but just in case).

I know we're fishing right now but hopefully we'll get a bite :)

Buy some MAF cleaner and spray some on the sensor:
spray some good and let it soak for a few minutes. Spray some again and let it dry.
Don't touch the sensor, just let it soak and dry.

40 psi is what you're supposed to have with engine off key on (per haynes).

If you're not loosing power as bad now, you must be doing something right.
If you have battery power at the pump, that's good.
What surprises me is that your fuel pressure seems right.

Yeah electrical cleaner should be fine.

Your pressure is right so I don't know if I would spend too much time on the pump. I know you said the car ran a little better after you tightened some bolts on the pump, but It could have been coincidental.
However, if it is a pump but it only happens randomly, well. It's going to be a pain in the neck to find that out. You would have to drive around with your fuel pressure gauge connected, and check your fuel pressure when you car starts to loose power. Maybe that would help to rule out the fuel pump once for all. But you would also need to know if your fuel pump is getting battery voltage when that happens to make sure it's not electrical.

Have you checked the back pressure, and the intake vacuum?
Just to check; do you still have the egr codes?

Hi there,

Sorry to hear you still have the same problem.
I should probably let someone else take over now since I don't seem to be able to help you.
I could make more suggestions, but I haven't been successful so far.
Maybe you could make a list of all the things you've checked and what data you've found (pressures, vacuum, voltage etc) so that whoever reads this post get a clearer picture of what's going on. Otherwise, we'll be shooting in the dark again.
Example:
*DTC: such and such
*Fuel pressure: 37 psi
*Compression:
Etc...