2006 Saturn Ion Transmission Clunking

Another user already posted this question but here is my story:

I have a 2006 Saturn Ion 3 with the 2.4L inline 4 cyl. With auto trans.

During 4th of July weekend I had an experience where after about 30 miles of travel when I let off the gas and the car shifted, it shifted really hard. After that whenever I would take off from a light (at reasonable acceleration rate), it would shift really hard, you could definitely hear and feel it. After I left the party I was at, it was fine the whole way home.

Well, it started doing it again the other day, so I took it and had the trans flushed out at 90K miles, I had the fluid flushed and the filter replaced at 45K as well. The fluid coming out was dark and smelled of burnt garlic, so my years as a lube tech made me think, "ok good, that was the problem and it should be solved now". Well, it happened again last night. It seems to happen when I am letting off the gas and decelerating and then in first to second gear.

On a separate note, my engine light came on and it had said that it was my cam position sensor, are these two things related?