2006 Daewoo Lacetti Strange Bounce

Hello. While coasting in top gear I let my foot off the gas slightly and the car seams like it does a deceleration bounce 2 or 3 bounces then it evens out. Applying accelerator again and it bounces again. Almost like an engine mount is faulty or the gear box is worn. Looking under the Engine there is a engine torque shock absorber do these become faulty. This only really happens in 5th gear. 5th gear I assume is direct engine power. As in the speed of the gear box matches the speed of the engine. The bounce feels Mechanical but there are no extra noises that I can hear. There is no pulling in the steering. Any ideas?