Been awhile since I had to ask for help, so go easy on me

So I have an 82 Camaro 305 / TH200. I had open headers for a while and had to find an exhaust guy that could make the bends to mate up my headers to my stock exhaust.
Engine has 77k miles on it, Transmission was rebuilt a few years ago.

With the headers open and me driving, it would shift fine... It was loud as hell.. but it was relatively smooth, until yesterday.

Yesterday, I had the exhaust repaired, and it seemed to drive home ok (two miles away), but today when I went to drive it down my subdivision it downshifted.. and just acted weird and that never happened before. I checked fluids and made sure they were topped off.

1) If I manually go from 1st, 2nd, Drive, it appears to be fine.
2) It almost feels like I have a manual shift kit in it, but I know thats not the case. (Where you put it in D and it goes nowhere, I had one in my 79)

What do I need to check on my end?

just looking for some basics troubleshooting help. I don't want to soak any more money into it unless its a paintjob.. haha.
Wasn't sure if they guy that did the exhaust may have bumped something I need to check.. Never owned a thirdgen before.

 

Take a look at the vacuum modulator. Check its little rubber vacuum line particularly.

 

Sadly, I was mistaken, it is a th200.

 

Bummer... IIRC those don't have a vac modulator. Not likely to be that easy, as, say, the exhaust rubbing against the rubber line to the VM and melting it, or something simple like that.

 

Make sure the TV cable is tight at WOT.

 

Thanks, I will check it out!

Buddy of mine works at a transmission shop.. said it sounds like a broken "Sprag" ... of course I had to look up what the hell that meant and it boils down to the tourge converter.. lol.

I will double check the TV cable though.

Getting started on a TH350 rebuild anyway as a backup.