I have a 2006 2.0L Turbo with 140,000 miles. Have had normal problems and repairs and car is in great shape and running well ( I love this car!} except for recurring MIL lights indicating cylinder misfires. Occasionally the MIL light clears itself. Dealer states, and I concur, that due to high mileage and gasoline quality engine has carboned up. Other than taking the engine apart and cleaning, they recommended running Techron through it a few times. I have done this in the last ten tankloads of gas, and it has stopped stumbling on cold start but still triggers the MIL light occasionally, usually on a cold start. Incidentally, my dealer states they have tried a new system running a cleaning solution in the intake in the shop for a period of time that has seemed to help several customers. They are trying to price this, but $300 is the rough figure at the moment. Any suggestions?