I am the new owner of a 3G tl with a fresh rebuilt trans with less than a couple hundred miles on it... I've had the car about a week now.. sometimes it runs great.. shifts great.. but sometimes it sticks a little bit and then the blinking d light comes on. I keep reading about the pressure switches and was wondering if that was the issue, I'm not sure if they were ever done, when I turn the car off the light goes off and runs normally until it starts sticking a little bit then the light starts blinking again. Should I take it back to the trans shop or what?

I keep checking fluids.. everything is where is should be and the trans fluid is as clean as possible as well.

Take it back to the shop and let them figure it out. No point throwing parts at it, especially since it was just rebuilt.

thanks! Hopefully they can do something for me

The D light means there is an electrical issue with a sensor that the trans is reporting to you! Have them scan the car and the code will tell you whats going on.

I ended up replacing the 4th and 3rd gear pressure switches on my own! Super easy and fixed the problem... i guess they were never done on the car or it'd had been a while!