What would cause my jeep to lose power - Jeep 2003 Grand Cherokee Laredo

You need to read the fault codes to point you at the fault. Can be caused by quite a lot of things.

Low fuel pressure ?
Blocked exhaust system ?
Clogged air filter ?

When you say it loses power, do you mean electrical power or engine power ?
You would need to look at the fuse boxes for a loss of electrical power, and use a scanner or code reader to check the computer for trouble codes for a loss of engine power.

I hate to tell you this but... If it overheated you probably have at the very least blown a head gasket. The best thing to do is run a compression check and that will tell all. Hope that helps

Have the catalytic converter tested.

I don't know engine size? The fuel pressures I found was 31--39 psi, 92--95. I would use a gage and check proper fuel pressure.
How long since over-all tune-up? Any applicable trouble codes?

Sounds like a timing problem, check timing and if off could be timing chain worn out especially if there is excessive miles(200,000 miles or more)

Most Jeeps use the power steering pump to adjust belt tension. there is a slide bracket at the bottom and a pivot bolt on top. adjustment is made by tightening a bolt at the end of the lower bracket. I have also seen this arrangement used on an idler pulley right below the pump but I may be thinking of some other vehicle.

No, the ignition coil has nothing to do with fuel pump.

Fuel filter is the main culprit when you lose power going uphill. Going level or downhill means that the engine doesn't have to work all that hard and doesn't demand much fuel, so a partially clogged filter can usually flow enough to allow the car to run smoothly. Going uphill requires signficantly more fuel, and if the filter is clogged up, it won't be able to flow enough fuel. This will bog the car down and cause you to lose speed. Change your fuel filter.