Thanks to Mike and Lenny for suspecting timing or distributor.
When replacing old for new engine block and playing clean and shine, note the '81 throttle body has a red plug cap over the lower vacuum port.
Never copy your '79 on reassembly, pull that cap plug and hook up the lower vacuum tube to the distributor. If you do you'll get a super sensitive throttle, have to post questions why, and wonder if you're nuts.
Phew. Back to just learning from mistraeks.