Hi everyone , I have 04 c 230ss with m 271 engine , original owner , I got 175K on the clock , been doing my own maintenance for most part( except all known recalls ,cams sensors ect) the most serious repair I just done is rpl conductor plate 2 weeks ago.nothing else major. For the last year or so Ive been chasing some little bugs like muffled sound at certain rpm under load (but not present if just raising rpm in neutral) , also at that same rpms there is a small purr(my best description) like intake mufflers? (or if there is some fluid in the way of air). I have replaced that muffler just down from airbox just before supercharger and no change. Never touched the kompressor yet although when i remove serpentine belt and spin it seems it don't spin freely( there is small resistance) Is my supercharger need replacement? I ve checked the oil in it and when removed plug it didn't poured out so it may be little on the low level. It's my wife's daily driver so when i get in it it seems like the power is down a bit.
Also when driving and coming to stop just before stop the engine rpm goes really low ( like it's going to stall but will not) just for 2 seconds and goes back up .it mostly does this with ac on. I ve checked 12$ hose- all good. Any help is appreciated

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