I have a 2001 ES300 that I changed both Bank 1 & 2 Oxy sensors because of Check Engine light on. Light is now off but the milage has dropped to about 3-4 miles/gal less than before. As a matter of fact, the milage was excellent with the check engine light on. The sensors were Denso. The engine runs as well as it ever did, but just poor milage. Anybody have ideas on what to check?