I have a 2002 EX-L with 83,000 miles. Recently, I have felt a "rumbling" while it is idling. In addition to that, I have heard a slight whistle coming from under the hood and have suffered a deplorable 13 mpg in the city at the best. My first thoughts have been a vacuum leak or an O2 sensor issue. The maintenance light has not come on at all, so I am a little perplexed. The air filter is new, and the casing is tight. Does anyone have any ideas on how to diagnose the problem? Or if you have seen this same problem, what was your resolution? Thanks in advance!