Buick Enclave Transmission Shudder. It wont do this at lower speeds so your Enclave can take advantage of the torque multiplication that a torque converter provides. If you feel shuddering then its the Torque converter.
If not then the problem is within the transmission. First of all it was choking got the catalytic converter cleaned and changed out plugs that seems to have solved that problem which then let us notice a intermittent shuddering. It is the result of a known issue with the 2008 Enclave--a defective wave plate.
Car shudders and has problems accelerating when gears shifts.
I have replaced the plugs and the stuttershudder did go away for a short period of time but it is back again. Buick Enclave Problems and Complaints - 7 Issues. In fact GMs communications are filled with information for the technicians. With your foot on the brake put the transmission in Drive and apply light throttle.