500sl 1992 asr problem

[Hai]

Hey all,
I received my car 500sl 1992 5L a few days ago and unfortunately there are some problems.
In the car, after a few seconds or minutes, the ASR light comes on and the car goes into idle mode and the engine shuts off.
Every garage I've contacted doesn't know how to handle this model, so I'm trying to do it myself and hopefully with your help.
I don't have a code reader yet but I check on the OBD 16 pin by pressing a button which gives me the 7 blinks. I have a code booklet, but I don't know exactly which one of the 14 options the code belongs to?
If there is someone who can direct me to the problem?
The engine shakes a bit and the rpm is a little unstable, nothing serious.
If the vehicle is stationary and the accelerator pedal is pressed even then the ASR light turns on and the engine turns off.
Thanks for any help.