[Dave S Texas]

I have logged no error codes but the loss of power when I reset the ECM.

If you 'reset' the ecm by disconnecting the battery....bad idea. Doing that: erases the RAM(learned library) and reverts the system to the PROM. That ROM programming was used for a brand-new vehicle/engine/sensors. Trying to get a 29yr old engine system to run on the values of a brand-new engine/sensors isn't the way to go. Put miles on the engine and let the RAM rebuild.
May I suggest you buy a Cadillac Factory Service Manual(not a haynes/chilton) for your car? ebay always has a slew of them...$25 and up. Having one to use is 'handy'