Max speed 100km/h and loosing power after 3000rpm

Jimnys arent great speed machines... and i tend to feel its most comfortable at about 55mph
They are certainly sounding a bit loud at anything above 3.5k RPM

Mine is fully serviced annually, and recently had a new cat and exhaust to the back... so mine is about as clean and unrestricted as a Jimny is going to get.

To my calculations your 12ltrs per 100km works out to be 23.5MPG... which is low, and a standard car should be nearer 30mpg. However at normal motorway speeds Jimnys are thirsty, which is half the reason i stick to 55mph

I'll go along with Adam on that, it'll happily trudge along at 55mph without complaining. After that things get a bit messy, noisy and thirsty (and bouncy). You buy a Jimny for the grin, certainly not for the performance and/or road handling.

On the lack of power tho', it should rev up freely and not run out of breath at 3K. It will be bloody thirsty, but it should keep on truckin'. Ooh, I feel a song coming on. Now where's those flared trousers and platform shoes?!

Try also air-filter change, it will not cost you much because you can do it yourselve.
Hopefully the gearbox is not engaged in 4 high (take a look on your dashboard).
Normally the Jimny can do 120/130 km/h but then you will be high in rev's.
If i were you and as was adviced already, change oil's and give it a full maintenance, that will not do any harm.
Maybe a "little bit" on your budget, but then you're shure that this is taken care for.
Crankshaft sensor could also be the reason, better to change it also.

Try also air-filter change, it will not cost you much because you can do it yourselve.
Hopefully the gearbox is not engaged in 4 high (take a look on your dashboard).
Normally the Jimny can do 120/130 km/h but then you will be high in rev's.
If i were you and as was already adviced, change oil's and give it a full maintenance, that will not do any harm.
Crankshaft sensor could also be the reason, better to change it also.
Maybe a "little attack" on your budget, but then you're shure that all this is taken care for.
Succes !

I know guys that Jimny is not for speeding but it is something wrong when I cant have max speed and power (up hills specially )
when I was talking about fuel it was city driving yesterday I went countryside to buy tyres motorway driving 150miles spent 28liter driving 100km/h (62 ml)
I tried to take of the catalytic me self but is welded and I will need to take of the half of the exhaust.
I went to mechanic and he told me that it is impossible to clean it he said that I need to buy a new one if I think that is the problem.
Can anybody tell me how I can clean it
P.S. I check the air filter and its new

Also check the tension on the throttle cable ul find it on the throttle body