It had been running ok for about 7 years. The transmission hasn’t been touched since then. I think we are going to pull the transmission and check it out.

Fixed
 

Finally figured out what was wrong with our 71 Torino. After pulling the intake manifold and resealing it, with no luck, replacing the distributor with no luck, rebuilding the transmission with no luck, I replaced the torque converter and that solved the problem. I put in a new Hughes converter with a 2000 rpm stall rating, fired it up and what had been idling at 900-1000 rpms was at 2000+ rpms. Slowed the engine down and took it for a drive. It ran perfect. I talked to Hughes, it seems that if the cam has a longer duration and a higher lift, this is a known problem and the solution is to put in a torque converter with a higher stall rating. Thank you everyone for your assistance in solving this mystery.

Thanks for the update..

Odd that with the old TC it seemingly idled at spec speeds, meaning no strained idle in P/N, then with the new it was 2kish. It would also seem that frictions would have needed to have been applied to drag the base idle speeds down, or the old converter was bad experiencing a drag pre stall..
Either way,, fixed is fixed!