Hey guys, I'll keep it short. My car is a 2002 bonneville SSEi with about 82,000 miles. I have several codes that I got from a scan at autozone.
P0300
P0171
C1236
C1245
C1248
C1281
C1282
C1287
C1288
I have googled each of these briefly, but can't help but suspect they are all related to each other because the check engine light came on the same time the service stability system message appeared. Can anyone steer me in the right direction? Any insight is very much appreciated

You have 2 emissions code.
P0300 is a random misfire on ALL cylinders.
P0171 is BANK 1 LEAN.

https://www.gmforum.com/obd-ii-troub.../p0171-284036/

https://www.gmforum.com/obd-ii-troub.../p0300-284040/

BTW, asking the same question multiple times across the forum is not good. I trashed your other one.

You have two sets of codes that are not related. One is for a random misfire, which based on the lean code you are also getting could mean your fuel pump is starting to fail. You might want to get the fuel pressure tested.

All of the "C" codes are ABS related, and for the most part are indicating electrical circuit problems. With more than one circuit involved I would start at the fuse block and make sure all the bottom connections are firmly in place with no signs of arcing.

Thought about it some more, and there is a very slim chance the codes are linked. Check the battery and the charging system output. A weak battery and/or a charging system on its last legs can create all sorts of seemingly unrelated problems.