In addition, if I change the code to setup the micro in expanded narrow mode, the problem goes away. That is, the address bus seems to hold properly before eclk rises. In narrow mode, I have PEAR=$04, MODE=$A0. In wide mode, PEAR=$04, MODE=$E0. Also, I am booting up in single chip mode and writing to PEAR/MODE to change modes on startup.
Maybe I'm missing something in the expanded wide mode setup. This is our first application in 16-bit bus mode, we've been using 8-bit external busses for years.