I recently joined the g6 community, purchasing a 2008 GT 2dr with 59k miles. I am no mechanic, but I can tell something is wrong with my car. Within weeks of purchasing this car I had to have my radiator replaced, and some crossover pipe- all was fine for a few days. Now my car has 64k miles and I am having this issue and the dealership cannot find an issue at all. I feel like my car jumps forward when decelerating, I can watch the RPM needle jump back up when downshifting and I can also feel it in my brake petal, as if I am sliding but that is just my thinking. Sometimes I feel unsafe when it does this, and it doesn't do it at any specific time like if the car was cold, or lower speeds..it just does it randomly. I do have a powertrain warranty until september, but my local dealership claims it is not the transmission. Can someone please point me in the correct direction? Once again, I am not car saavy...I just need my car fixed knowing this is not normal.