Loss of power when going up hills ???

There is a hill near where I live which I have to go over to get to a near off roading spot I use when I first got the Jimny it used to fly up that hill no problems!! Now it takes forever!! And I'm changing between 1st and 2nd gear to get up it! And it has started to get really hot because I seem to be pushing it within an inch of its life!!
The revs just seem to really drop off as I'm climbing the hill! It's quite hard to explain.. Sorry I'm not the best with explanations :dry:
Thanks

To get really hot?.... Does it overheat? Where is the temp gauge position?

It gets around 3quarters on the temp gauge and no it's never overheated! I wouldn't let it get to that point as I don't want to destroy the cylinder head! Lol

Hhhmmm it shouldn't get that hot regardless of how hard you work the engine, that needs some investigation. Have you recently lossed and had to add any water ?

No not at all I check the oil and water regular and it's not lost any fluids recently! I've checked the usual "head gasket" faults and everything seems fine!...
I will keep up on the checks!

What mileage has the engine done?

If the thump gauge is going upto 3 quarters when worked there us a problem there that doesn't want to be overlooked, it may even lead you to the poor performance.

Check circulation, viscous fan operation? Remove and test or replace the thermostat, if cars run hot then they don't run as well as less fuel is delivered to the cylinder. The thermostat might not be opening fully holding coolant back causing as temp increase.

Failing that a compression test, and the only way to test and eliminat head gasket frailer is to do a cylinder leakage test.

Steve.