During the past month, my 2000 RX300 with 69,000 miles was having difficulty starting up particularly on warm afternoons. One afternoon, it would not start after repeated attempts, however after several hours of rest, I was able to start it although it would shut off if I let off the gas pedal. Once on the freeway, it ran nicely. The next day, I took the vehicle into my mechanic who discovered that the magnet for IACV was so heavily gummed up, he was not able to move it. The repair bill came to $135 to clean the IACV. My mechanic indicated that a Toyota dealership typically will replace the IACV instead of cleaning which is quite an expensive part but he stated that the IACV gums up about every 60,000 to 80,000 miles and there is no need to replace them – just clean it every 60,000 miles. After I picked my RX300 and drove it onto the freeway, I immediately noticed a big difference in the response, smoothness and power. I have read other threads in the Lexus Forum about IACV related problems and some attempt to fix the problem by putting in a fuel cleaner into a tankful of gas. The IACV does not receive fuel but takes in air and can only be cleaned by removing the IACV.