Trasmission Trouble.. Maybe? Help

[Abear]

I have no Idea whats goin on. It started..Saturday morning when I left for the dyno. I was bringing my sister to get her rental car and when I got in the car and started it up and shifted to reverse, the car went into reverse hard. At first I figured it was just cuz it was cold because it did it again when I shifted to drive.

When I got to the dyno, I was moving my car to get it ready to get on the dyno, and the car started studdering like it was running out of gas. Course the gas tank was nearly full. The dyno guys turned the car off and let it sit for 5 minutes and then tried it again and everything was normal. On my way back to my house today, I had the car on cruise control and I was going about 65 and it started studdering again..cruisin at 65. I have no Idea whats goin on, the only thing is the CELs on and its an O2 sensor, and of course I just installed the SAFC2. But Ive had the SAFC2 on since Friday morning and nothing was wrong all Friday. The only thing that changed between Friday and Saturday was that it was below 40 degrees Friday night. It has been really cold like that the past few nights.

At first I just figured it was the that the car just needed to warm up, but that therory was disproven today driving home since it studdered at 65.

Does any know whats up?