Fuel Injection problems of the 2005 Mazda Tribute

With just over 12000 miles, the throttle became very sticky in cold weather. The butterflies in the throttle body hold the accelerator pedal closed, requiring excessive force to push (and excessive acceleration). In cold weather, throttle would stick closed whenever the pedal was released, no matter how long the vehicle was driven. The dealership (hall Mazda in virginia beach) replaced the throttle body, and commented that the throttle body should be cleaned every 12000 miles for varnish buildup. There is no TSB that I could find on this problem. I believe the problem is the pcv system, allowing oil to collect on the throttle body, and causing it to bind during cold weather.