I was kn the highway a few weeks back and ran my 1984 trans am a little hard. It's the 5.0l 305 carbourated version, and I hit probably in the range of 90 to 100 while I was driving. I noticed on the way to my destination that my acceleration was a little iffy, but once I got back in the car yo leave is when I REALLY noticed it. It only kept getting worse as I drove home, untill my 4 second 0 to 60 turned into 15 second 0 to 40. RPMS bounce around a little between 900 and 1300~ at idle, when driving now I'm shifting at about 3000 to 3500+ instead of about 2000 like previously. Still almost no acceleration.
I have so far:

Cleaned the carb (helped a lot, when I first brought it back from the highway it would shake the whole car but now it's more gentle.)

Replaced fuel filter
Replaced spark plugs
Replaced spark plug wires
Replaced valve cover gaskets
Replaced fuel pump
Replaced vacuum lines

Even with all this, it has most definitely improved in its running condition, but still very iffy. I can post pics and send videos of whatever yall might need.
Thinking it's a vacuum leak somewhere along the line, a fuel delivery issue or a misfire issue which would have to be distributor caps and/or rotors.

 

I'd pull the valve covers and check the valve action. See that all valves are opening nearly the same. I'm thinking the cam and lifters are on the way out.

 

I can check them, but the car only has 60k original miles if that would change anything. I'd think the major engine components should be fine, but it's also 40 years old so you never know. I'll see if I can check them this sunday

 

Make sure you didn't lose a bunch of timing from a loose distributor. If its not bolted down tightly they can spin. Might want to check base timing. Agreed with checking the valves. Does the exhaust smell any different?

 

Replaced the distributor cap earlier and she's runnin great now. Still some issues with rough shifting, thinking the trans filter needs changed. Talked to the dude I bought it from and he never did any major service aside from fluid change, 60k original miles on a 40 y/o car. So most definitely is way past overdue.
Aside from that, the only issue I've found is a slight whisting from the engine bay, doing a smoke test tomorrow night to find the leak (assuming it's a vacuum leak).
Thank yall for the advice, I'll still be checking on those things yall mentioned just to be sure everything's good since this csr really didn't get any major service done to it untill I did some things recently.

 

Once you find and correct your vacuum leak, put a vacuum gauge on it at idle and post your readings. Pay attention to any fluctuation at idle.
Vacuum gauge is a cheap, old school diag tool that will illuminate bad valves, lifters, cam lobe, timing, etc

 

Also, you may want to have someone press the accelerator while you watch the travel at the carb. Given your description of the shifting issue, you may have a stretched accel cable that isn't giving you wide open throttle but is still to the floor