Do you keep a rag wedged into somewhere in the engine compartment?? Or is there a rag you don't know about from the PO??
Is the lint the same color as the air filter?? Or the engine compartment insulation??

I found a mouse's nest in my grandma's E420 in the V of the engine. It was made from the engine compartment insulation.

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All it takes for evil to prevail is for good men to stand by and do nothing.

Too many people tip toe through life, never attempting or doing anything great, hoping to make it safely to death... Bob Proctor

'95 S320 LWB
'87 300SDL
'04 E500 wagon 4matic