I think Paul is on the right track, but one thing he should check first is the fuse in the overvoltage protection relay. It is a silver colored relay on the right side or the engine compartment near the firewall that has a plastic flip up lid. If you flip up the lid there is a common flat fuse (15A I think) inside. It was not unusual to have this fuse blown during a battery/ jump/connection misadventure. If it is blown the CIS E module will not have power and it will cause the engine to be very hard to start cold because there is no cold start enrichment. After the engine warms up it runs fairly well since it is an electronically assisted mechanical fuel injection system (Bosch KE). All of the US version 190s had fuel injection, although I think there was a carburetor version of the engine sold elsewhere in the world. I owned a 1985 190 that served as my work/home freeway flyer for many years. Worth a look anyway.
benzdoc