fuel distributor replacement
In my attempt to correct a persistent rough idle problem on my '86 300E, I am faced with replacing the fuel distributor. My mechanic says the #5 cylinder fuel feed is not correct. In fact he swaped out the fuel distributor with a known good one in his shop and it corrected the rough idle. He has a very good reputation, so I trust him in this matter.
All other possibilities have been checked, including fuel injectors, wires, plugs, cap, rotor, compression is even, motor mounts are new, OVP relay is good, fuel filter ok.
I bought a fuel distributor from a u-pull it for $150, which was attractive considering the alternatives ($1327 at dealer!). They even gave 30 days to bring it back if it does not work.
My question is this. I am confident I can swap the distributor out. What other things must be adjusted or checked after replacement? I can check lambda using the duty cycle method. Any other pitfalls?