One problem related to vehicle shudder has been reported for the 2001 Mazda Tribute.
Vehicle Shudder problem
1 At speeds around 40 to 50 mph it feels like the transmission is slipping weather I am accelerating or coasting. I also see the tach needle jump around when this happens. The slipping feels like a vibration in the vehicle and there is a lost power. Past this speed range or before it the vehicle operates normally. Dealer could not fix or reproduce the problem.