Please Help Me, Huge Power Loss

Hello All,
Struggling the diagnose this problem. Recently I have experianced a loss of power with my 1999 Jimny G13BB. This is noticeable over the entire rev range and all gears, but is more pronunced at highway speeds. I cannnot maintain 100km/h or even 80km/h when going up a gentle gradient on the motorway. Initally, I thought this would be the catayltic converter so I cleaned this out to see if it help but no change. I also changed the Spark Plugs and Air Filter but still no difference. The engine does not idle rough nor miss a beat at any revs or gear, it simply doesnt seem to have the power anymore. Still revs to its normal limit too. I would greatly appreicate any suggestions on this issue, as I am begining to run out of ideas. Thanks in advance, Tom

Possibly a fuel starvation problem. Are your injectors clean? Can you rev the engine up to 6,000 rpm? All sensors still connected? Did you check the gap on the new spark plugs?

Do you have a compression gauge? Are there any deposits on the plugs? Have you checked the ECU for diagnostics fault?

Is your clutch slipping? Easily checked with handbrake on and engine in gear, release clutch and see if it stalls promptly.

You haven't done anything you should tell us like fit 33" tyres?

My first thoughts would be fuel starvation. You may have had a bad batch of fuel, or let the tank run dry? I would check the fuel pump and filter.

Also, since its free and easy, check if you got any brake drag.

This is usually caused by a blocked catalytic converter.
How did you clean yours?

Thanks a ton for the fast replies.
I haven’t physically checked the injectors yet, but will do this tomorrow. All the sensors seem to be still connected. I checked the gap on all the spark plugs as I installed them so I think that should be right.

Will see if I can borrow a compression gauge of a mate of mine to check that out, the old plugs didn’t seem to have any build up.

Going to put her in to get the ECU diagnostic done as soon as I can this week, but was trying to rule out all the simple or common problems first.

Clutch doesn’t slip at all, and if I had 33” inch tyres the world would be a better place haha, I might even put up with a little bit of power loss.

Truthfully, in ‘cleaning’ the catalytic converter I simply removed it completely from inside the exhaust just because I thought that would be the quick fix for it. But cleaning it that way works wonders for freeing the flow up haha.

Has anyone had any experience with checking the fuel pump and filter before?

Well turns out it was the crank shaft, the mechanic advised me that I should replace the whole engine at this point so I guess thats the holiday project now. Has anyone ever done a petrol to diesel K9K conversion?