That particular model (all 92-95 W124 and W202 cars) have wiring harness problems that can cause all kinds of wonky symptoms, including bad engine miss. Often, as the engine rocks slightly under load, the harness is moved and the problem occurs.
The insulation on the harness fails, and the wires become exposed and frayed. As they short, various problems occur. It can be inspected visually, and the dealer should have done it, but some do not perhaps hoping not to admit that this is a pattern failure on these cars.
I'm not saying this is what the problem is, but check it out before throwing parts at it. Also, the dealer is "guessing" that one of those components is the problem?
That's NOT the right way to do it. They need to FIND the problem first. Eliminate the easy stuff (visual stuff like the wiring harness) and then really get into the problem.