Crazy alignment problems

A '68 torino owner described almost the same issue you have.
He also said he'd replaced everything in the front end a couple of years ago but hadn't driven the car 'till recently.
He also said he'd hear a clunk sound when the front end would shift.
He finally noticed his new pittman was sliding up and down when moving forward or backing up.
On his car it was radically changing the toe setting.
I'm telling you this to remind you not to assume that new parts can't be the problem!
So check everything again, lift the car and try to move each wheel, something is either broken or loose.
make sure the upper control arm attachment pieces are sill completely welded to the fender apron, I've seen these welds fail.