Hard Shifting w/ Service Engine Soon Light

Hello All! Hope everyone had a Merry Christmas and Happy New Year. I thought mine was off to a good start until today when I happen to take my son to school and soon as I jump in the 95 Aurora w/ 172,000 miles it started acting funny. I drove it about a mile down the road when I noticed it shifting into gears at little bit higher RPM's causing it to jump a little. I drove it like that just thinking everything might have been cold and you know just acting funny. But then I went to back it into my dirve way when KA...BLAM!!! It felt and sounded like I just got hit from the back of the Aurora. So I then turned it off and let it sit for about eight hours until I had to go back to pick up my boy. And as soon as I started it "Service Engine Light" came on instrument panel above cluster. And It Shifted very hard from Park to Drive. I notice it hits the hardest going into Reverse! Drive is pretty bad but not as bad as Reverse. I did some searches already and didn't really find a good anwser. Everyone in the threads seem to just stop before they said what may have fixed it (if they did). If anyone has any good info they like to share about this problem it would really help. I am a little bit of a pickle with money so the cheapest way would be the best for me. Thanks in Advance! And Hope everyone stays safe out there (Aurora's too)!

Need the codes to proceed here.

If my memory is any good, I think the owners experiencing this traced it to a bad turbine speed sensor in the trans.