Just bought a friends 94 Van, beautiful condition, 94000 miles, 6 Cyl.
Only one key and remote. Another key was made, and worked fine. The
second remote was purchased used on EBay ($12), lots of opinions on
how to program. What worked was the two wire connector under the dash
W/y,G/y. Shorted, the ignition on, the locks cycle, pushed one button
on each remote, lock clicks. Turn ignition off, remove short, locks
cycle again, and everything works fine, both keys, both remotes.
Newer models require off-on cycles(07 Focus).
Hope this helps us older owners (car and self).