another m103 idle problem
 

hi guys, I know maybe there were a lot of threads covering this problem.
I just bought a 89 190e 2.6 auto. the old owner lives 600kms away from me, so i had to drive the car that far to bring it home, i felt it hesitated going uphills and the economy needle is halfway at idle and it was very lumpy and missfires on idle. so the next morning, i read every suggestion i could find on the forums and i checked all vacuum lines and replaced all the leaky ones including the ones going in and out of the icv. took off the fuel dist and clean the butterfly, icv and the throttle. changed the plugs(ngk bp5efs), leads, distributor cap & rotor, air filter and 15w40 mobil oil & filter.
i adjust the lambda tower, to make it leaner, becau se theold plugs aretotally black , the car runs much better w ith only slight shakes on idle. after a few days driving, i looked at the plugs they seem to run a bit too lean and if i richen just a litle the idle gets very lumpy again.
should i lean the lambda tower and open the EHA a litle? or is it time for me to get a duty cycle meter and have a proper check? thank you