[tba]

Just above MAF in my CLK 200K there is a rubber hose connecting to inlet ducting. Inside that hose I found steel collar covered in some oil (as one could expect). My question is if that collar serves any purpose or maybe if it's some modification done by some mechanic for some reason?

(random picture of similar engine bay https://images64.fotosik.pl/652/8f7ecc17041db1f3gen.jpg)

 

[tba]

I noticed same steel ring fitted inside plastic elbow above MAF (point A), so I guess I solve this mystery. Ring's out. Car responds better (or maybe its the new air filter).