Toyota Repair: 2001 camery idle problem, mpg city, fe engine

Question
I bought a 2001 camery xle,with a v6 3 ltr (1mz-fe) engine in july,it has 110000 km {about 70000 miles)on it. When I start the car the high engine idle always engages in morning and after the car sits for a couple hrs, this occures in warm and cood wather. It stays on too long and also causes a late shift. I will drive 2 or 3 miles before it comes off.I feel the milage is low,about 20 mpg city and 33 hwy.I bought the car from a dealer,they say every thing is ok. My question is, would this idle problem cause the low milage in town?

Answer
The most common cause for idle problems on camrys is the idle speed control valve located on the throttle body, these can get carbon build up on the inside and hang up causing either a high or too low of an idle speed, the ISC valve can be removed and cleaned with good results.