does it sound like a CPS or a CS problem?

my 06 745Li with only 60K miles was giving me problem yesterday. On the way home, it certainly became really sluggish, the check engine light came on and a quick message about a transmission issue that i can't recall. i pulled to the side and turned it off. I then restarted it right away and the car vibrated like it was not running in all 8 cylinders and the check engine light was still on. I shut off the engine for about 8 minutes and then restarted it. This time the car ran smoother but the check engine light was still on. I drove it slowly and made it home. I have not plugged in the OBD2 scanner to see what the codes are since I didn't know where the obd2 port is. I think I do now after some searching, above the hood release handle.
Does it sound like the CPS or CS problem? Depending on the codes, would i need to replace all 4? Is it easy to do. i had done that to a mercedes E class but it had only 1 CPS.
Any advice you could give me, I truly appreciate it.