Hello guys,i drive a 500SL '93,,,and it kinda overheats a little above 100 BUT ONLY when i stop in traffic lights or when there's a traffic jam.... and its anooooyinggg...i notice that when i stop totally and my gear is on D the rpm is low..about 500rpm...(with AC and gear on D)..when i put to neutral goes a little up...and when AC off goes to normal...around 750rpm.. i want to know what is causing my low RPM..thank u for reading and i hope u can help...