When dropping a carbureted motor into an 89 Trans am that originally had a 5.0 TPI, will the ecm still work for the automatic transmission or will I need a lock up kit? Is there anything else I need to know to avoid problems with this swap?

If you have rendered the ECM inoperable (which I suspect you have since it was made to control a TPI and not a ccc carb) you will have to install a non-computer distributor and a non-computer TCC lockup system...

ECM or not...

The Torque-Converter Lock-Up circuit only consists of 12v Positive and Negative...
No PWM or anything remotely complicated.

Run the Positive wire of the solenoid through the transmission case pass-through connector, inside the vehicle, through the Brake-Pedal switch, and to switched 12v (ignition).

Run the negative wire of the solenoid through the transmission case pass-through connector, through a vacuum switch to a ported-vacuum source, and then to a ground point.

There are multiple threads on this forum that go over the parts (vacuum switch, brake switch, TCC connector, Etc) and procedure...
Just do some searching.

I use a pressure switch in the 4th gear oil pressure port (early 700R-4). No vacuum switch. The brake switch is already switched 12v+ with the key. It's a purple wire on my '83. The ECM completed the ground connection, but with this setup, it's grounded to the transmission case and the pressure switch completes the 12v+ connection in Overdrive when the designated pressure is achieved. Hit the brake, and the power to the TCC is immediately interrupted and it unlocks. I got the kit from Momster Transmission...