Since I have owned it the 190E has had a variety of annoyance level running issues. Initially it was virtually impossible to start but ran fine once it got hot… I later realized the ECU was unplugged! Turns out with CIS the ECU is really only there to do startup enrichment and cold start stuff. Lately the car has started fine but won’t stay running when cold AT ALL. Ie it fires on the first crank, revs to 1500ish, then dies immediately. Keeping it going when cold is an exercise in throttle feathering, but once it warms up it usually stays idling fine but the idle speed is a bit erratic. I had previously fixed a number of broken wires, cleaned the idle valve and cleaned all the relay and fuse contacts, but seen little improvement.
When I first bought my 1985 190E 2.3-16v (back in 2010), the A/C worked. It didn’t work all that well though, and I assumed it was a bit low on refrigerant. It spent a year or so up on blocks while I did a bunch of things to it which should not have taken a year, but after getting it back on the road the A/C no longer worked. Inspection showed that the system was completely empty now (zero pressure at all).