1990 300e rough idle
 

neighbor saw me working on my 300d and asked if i work on MB. i promptly answered "mine". asked me again so i said i'd look at it but i didn't know anything about e class cars. so took it for a drive. nice car. the engine had been replaced. some one had "borrowed" it, took out the oil pan and kept goinghttp://mbca.cartama.net/images/smilies/frown.gif.

any way "new" motor was running fine till car went to a body shop???

so i looked under he hood noticed that there was an sensor in the "Duct" going into the breather. well that wasn't hooked to the breather. figured the sensor was a MAF. in which case it wasn't giving very good info. reinstalled it but car continued to idle rough and occassionall surge.

car runs fine at speeds but on exceleration stumbles initially, slight hesitation then picked up like wow.
on heavy decel, no problems till it got to idle. dipped then came back up rough. you could feel it vibrate.

so, how do you read the codes?
do you need a "special tool" or does a light flash some where?

i've searched the forum and found several maybe's, but the solution seemed to be replace the part and see. is there a beter way?

whats the most likely culprit?
who universal are the parts on these things (ie will i find the same sensonr on several cars with this engine or even other engines?)


thanks