Hot rubber smell

I have noticed the smell of burning rubber from under the hood...suspecting serpentine belt...checked tensioner and all pulleys for that matter and they all seem to turn freely....smelled it the other day after running engine around 2000 rpm with hood up...looked in engine compartment saw no smoke...shut off and felt belt but did not feel hot....any other suggestions?...I have smelled this before...usually when engine is under higher rpms....like going uphill...but lately a 20 minute drive anywhere and I can smell it...2000 blazer 4wd 4.3 auto...no cracks in belt and was replaced a little over a year ago..

Are you sure it's not a oil leak dripping on exhaust? This can give off a similar smell.

Nope...definetly a rubber smell....it has actually done this for a while now...I mean like a few years...oil is always full....like I said at higher rpm or under load is when I really smell it...kinda irritating not being able to track it down..