Noises and Rattles in Old Mazda

I have a 1995 Mazda 626 with lots of miles on it, trying to limp it to its 200K retirement.

I had been having a vibration at 60-65 mph and decided that this might be due to a very bad lower ball joint that has needed replacing for seom time now. I had the ball joint replaced and the mechanic also noticed the torn boots on the CV joints (I knew about that problem too) and shot me a price that was good enough that I had both CV/axle/boots replaced.

Now, in addition to the vibration at 60-65 mph, I have a much more noticable vibration at 20-25 mph and a noise (sounds like a helicopter) from 30-40 mph; the lower speed noises/vibrations occur on acceleration, not noticable on decceleration.

I called the mechanic back, described this set of symptoms and he suggested I probably had a bad tire. Did the requisite rotations and when that failed got 4 new tires. Guess what? Still have all the noises and rattles!!

What’s going on here?