My es300 died while turning corner. I read the club posts and learned that the problem might have to do with idle control valve. The repair shop (not dealer) also recommended a major tune up (replace spark plug, ignition wires and clean injectors) to fix the problem. Since this car has 90K miles on it, so I also had timing belt replaced there. It costs me close to 2K total. A lot of money, but I am hoping it will last for several more years. After all of these have been done, I noticed that humming noise coming from under hood when car is in idle. I took the car to the repair shop and they adjusted the timing belt. Now the engine is quieter when it on idle, but when shift to Drive, I can still hear the noise. I took it back to the shop and they told me that timing belt was OK and the noise might be coming from A/C compressor even when the A/C is off. I'd truly appreciate for any ideas/suggestions of what may cause this noise. Thanks.