Before you install new parts on trial and error basis, I would once drive to the dealer for a real fault code analysis with the computer system. Let them explain all the faults, drive home, buy a Bentley Repair Manual for the E36 and start repairing it DIY and buy the parts from the usual online shops.
What does error code P0302 for the check engine light mean?
P0302 means number two cylinder has a misfire,
What does error code P0302 for the check engine light mean
Causes
A code P0302 may mean that one or more of the following has happened:
Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer
If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. There are also cases that the problems were faulty fuel injectors.