This sounds like an M103 but, either way, I agree with MBDoc.

If you're going to keep the car, ensure you have the entire HT system up to scratch:

Plugs, Distributor cap and rotor, HT leads.

Go to MB, ask for discount and get the HT stuff from them. I have and all my hot problems have gone (in fact, I have Beru Silicon HT leads and these seem fine).

Also check any temperature sensors. If you've got the M104, check the air intake temperature sensor - €12 from MB.

Once the HT is in fine fettle, take it from there - these engines demand the best HT components.

RayH