Automatic Transmission Cooler problems of the 2002 Mazda Tribute

This vehicle was taken in for problems with the engine missing, "firing" and vehicle bucking- at any speed and gear. A leak in the transmission was discovered (almost all of the transmission fluid was gone) and I was told it was a manufacturer's defect. They fixed this problem, but the vehicle continues to run the same way. I have been told that all of the Tributes run like this and it is normal. . . I have contacted the Mazda customer assistance center and have a case number. . .