Volvo 850 2.0 stutters, 4 cylinders, no MKL!

Moin to everyone, read here for a long time with and with my first thread I need help from you immediately. I drive, among other things, for about 3 years a Volvo 850 2.0. Purchased with approx. 290tsd KM and after a short time I was allowed to have the clutch replaced first. Now he has approx. 350tsd on the clock and was up to now absolutely no worry child. TÜV e.g. 1.5 years ago passed without defects. At all I was very satisfied with the Volvo – no rocket with the engine, but cozy and cult. Now catches The engine is stuttering and has no power, it seems to me that it only runs on 4 cylinders. Besides, it starts badly. But the bad starting behavior has been present for a long time, so perhaps a separate error. I imagine, however, that it has become worse. So it should be something with the ignition or injection, I mean at least. But the MKL would have to start there? Doesn’t it… spark plugs 35tsd KM came new, also a distributor cap and finger. The ignition coil looks good, not started or striking. So a week ago I quickly changed the ignition cables on the side of the road. During a short test drive I had to overtake a tractor and turn almost into the limiter. After the speed orgy everything was back to normal and it ran as before. Unfortunately, this only lasted until yesterday morning and the engine now runs like a sack of nuts again. For every help I thank you here, because the car is also our workhorse and is needed almost every day at the moment. So thank you very much in advance…