Those new 16 inch wheels you just spoke of, did you put those on the front,
too? No harm in loosening and retigthtening the lug nuts. That is a common
reason for pulsating pedal.w Causes warped rotor or drum.Maybe crud on the
drum exterior where it mates with the new wheel can cause this.Wire wheel
or brush it off.

 How did the drums go bad when all you did was take them off and replace
the shoes, then put them back on?  Did you put the 11mm bolts back in when
reinstalling the drums? Is the tire out of balance?