Hello
I have a 1992 seville sts 4.9
And i have a problem with it that have come the last 3 days .

The engine goes a but unregular on the rews .
And the last 3 daysit loves to stay at 2500 RPM and is a hell get down to 800.
And when rews get high the engine service soon lamp turns onand goes off after a while.
It dosent follow the cruse control either, well if i have set it at 70 km/h and brake down to 50 and press resume it goes as fast as possible up to 70 ( a bit unsmoth sometimes also) but the engine still loves climb over in speed. u can let the gas be and dont touch it at all it still climbs up slowly.

Did start the car up today after work 27 degress celsius varmsunny nice weather . it goes fast up tp 2500 rpm then efter 5 sec down to 1500 then 3 sec more 1000 .
But then when i drive it is as a typed above have to keep braking keep the speed down time to time .

This isent a new car and it is my first American car. Had it for 1 year now and like it damn much .

Anyone that can help me what it can be and how to fix thisor suggestion what to do or what it can be ?

Have to say workshops/spareparts isent common herefor this "rare car"(i live in sweden)

Sorry if my english isent perfect // many thanx Stefan

 

I had the same problem with my 94 seville sls a few years ago. It would go up to 2500 rpm's and would overheat. I found out it was the idle speed motor. I got mine replaced and the car was fine ever since. Another problem I had too was the engine speed would go up and down, not too much, which was a problem with the computer. I had that replaced too.

So I would try the idle speed motor first. Hope this helps.