Update - Bought a 01 Grand Prix PCM and got different codes. P0412 and P0418 (or something like that). Returned that PCM when I found out the salvage yard got in a 03 Grand Prix PCM the following week. Swapped for the 03 GP and BINGO! No codes, no dummy lights, and motor runs like a motor with 1400 miles should! Posting this for someone who may run into the same issue!

Thanks for replying to my posts, guys! I appreciate the help!