1985 500SEL Starts great but idles around 1100-1500 RPM (used to idle about 800) Some times it's about 800 and some times it is arround 2000 nut it is usually between 1100-1500 and I can't pin down any sort of pattern. I am not sure if this is a related issue or not but the Economy gague on the dash is always in the red evev when idleing near 800. any ideas? I did not buy this car to save gas but with gas prices the way they are I can aford for it to be burning more gas then it is suposed to.