1998 Ford Expedition starter problems

Intermediate starter problem, when I try to start the
selinoid switch relay clicks, I have replaced the
battery, starter, selinoid relay, starter battery cable,
ran a 4 gsuge ground wire from battery to bolt that
has starter ground wire on it, pulled starter (brand
new) had it tested, 2nd replacement of selenoid
switch stripped negative cable and replaced
negative battery terminal.  Tried to jump the
selenoid switch, it only clicks. Everyone I try
something and put it back together it will start fine.  
Then after a few days back to same problem. I am
going to try and check the ignition switch to see if I
am getting power to the starter from the key.  one
other note when I started having problems and
replaced the starter a key I gave the mechanic had
lost its programing.  I have 2 other keys that work