i have never had trouble with tmz, even very out of date tmz.
about a year ago i used it ( at 3200 ) to document a roasting of sumatra
and then brewing of the same coffee that i typically use as my film developer.
the tmz that i used was stored on a shelf or drawer for 15 years or so
here are the results:
back in the 80s and early 90s when i used it often i would shoot it at 3200
and it was fresh, and i'd process it in a conventional developer ( tmax rs, xtol, sprint )
and never had trouble either ...
all in all, i have learned over the years to have low expectations
so sometimes i am pleasantly surprised.
sorry for your troubles !