This issue happens about once every 2 days. I stop at a light and the car feels fine. When I try to accelerate I feel this sudden shaking. It will last about a second. It fells like I accelerated the car in neutral and changed gears when the acceleration was high. I am afraid it is related to the transmission. I took the car to the shop and they replaced 2 engine mounts that were broken. I thought that was the problem, but The problem continues. Since the issue occurs randomly, it is hard to show to anyone else.

The car is 150000 miles now. Other than that, it is working fine. I will like to know if someone is having a similar issue and if they found a root cause to the problem.
Thanks