Your engine is designated by the MB code M104. Do a search on M104 AND oxygen sensor and you'll find a bunch of stuff instantly. Also search for M104 AND wiring harness, and m104 AND idle.
Sorry I don't have the answers but you will soon. Welcome to MercedesShop.com!
In case you did not know you can buy the PARTS you need from this site at great prices, click on fastlane and find them. If you are lucky, there will be a pic of the O2 sensor. If it is not listed call Phil at the 800# and he will get you the info quick.
RIP "Betsy" (Oo=*=oO)
'96 E 3 2 0 (W 2 1 0) M 1 0 4 (Totalled)
Spaces in sig so as not to screw up the SEARCH; every time someone searches for that MB they don't want my sig!
2004 Audi A8L
'98 VW Passat 1.8T 5M
'87 Alfa Romeo Milano 2.5L 5M
'67 Impala convertible, 327cid