Car Throttle Sticking problems of the 2005 Mazda Tribute

When apply full or almost full pressure to the gas peddle the throttle sticks causing the car to speed forward and the brakes do not engage fully to stop the vehical. Thhis happened 3 times so far. I had use the emergency brake. I had the recall repair done this occured after it was done. They did something to the engine cover but later had it removed because I thought that was still it. But even without the engine on the car the throttle still sticks. Dealership says it does not know why I am having the problem.