Suzuki Jimny 2005 automatic powerless on highway

We replaced the throttle because it had problem. We checked that with the diagnostic tool and the code was fort the gas throttle. So we replaced it but nothing happend only the lamp turned off. The only modification is general grabber at3 tires 205/75-15. There arent any smells from the gearbox, only sometimes som smell from gas. In N its revs good no problem, but when you are on the highway you cant go more than 90km/h and the car havent power to rev up more than 4000rpm i dont know if its with 3rd or 4 gear. I dont think its normal i dont know any other with automatic gearbox in Sweden. And its not big hills its very low gradient hills. Its the highway you Can not Call them hills the seller who sold the car to me told me its a new Exhaust and cat. I dont know what to do, i have booked an checkup on Suzuki 8/12.

Here is some photos of the car 

The code you have P0121 is stating that the throttle position sensor has a range problem, see the following obd2pros.com/dtc-codes/p0121/

The following text is taken from this link

Causes

There are a few primary factors in your vehicle that may cause a P0121 trouble code:

That the TPS has an intermittent up or an internal short.
That it is rubbing the harness and causing a short or open in the wiring.
There is a bad connection at the TPS.
That the PCM is bad (although this cause is less likely).
That there is corrosion or water in the sensor or connector.
Any one of these could trigger a P0121 trouble code to occur.

Symptoms

There are a number of symptoms that a vehicle may be experiencing, should a P0121 trouble code be present with the vehicle:

The check engine light comes on.
The ECM will cause the check engine light to come on. This will put the vehicle in failsafe mode, which means that it will cut off the current to the throttle actuator, put the throttle valve at a little less than 6 degrees of an opening.
The ECM with control fuel injection and timing to control the speed of the engine.
You will be able to drive your vehicle, but only slowly and with very limited response to the throttle.
The engine may not accelerate as smoothly as before.
The engine may idle higher than it normally does.


This seems to fit, your Jimny is running on reduced power or reduced throttle opening. The links suggests checking the sensor, but also the wiring.

Robin

hi and thank you very much for your help, it is very much appreciated. when the lamp was lit, the car went into safe mode, it then had no power at all and did not rev high at all. then I left the car in the workshop and they replaced the throttle house and tps sensor. if there were still problems would not the lamp start to shine again? the car has power at low speeds. from the start it is very alert but as soon as there is a small hill it loses speed.

I would try to take a video tomorrow and post it here so you can see what the problem is and how it works.

I can also tell you that the fuel consumption is very high its about 11-12L/100km with 35L i do maximum 300km.