Tank Assembly problems of the 2008 Mazda Tribute

Accelerator pedal is sticky. It becomes very difficult to push, then will suddenly release and allow you to accelerate. Happens every morning, and lasts for about 5-10 minutes. Condition is worsening. Dealer "cleaned throttle body", but it did not fix the problem. I returned the vehicle to the dealer who said the throttle body should be replaced. Mazda extended warranty initially denied my claim for repair stating "not a covered part". However, they now say it is a covered part, but still have not yet agreed to pay for the repair. I was told that if I pay $100 that the dealer would run some type of cleaner into my gas tank, but with no guarantee it would work. This would not be covered by my extended warranty. A badly sticking accelerator pedal should now be classified as a safety concern!.