where is the plug for 2003 ford escape block heater located?

Did you have one installed?

check behind the front bumper look through the center of the lower grille

if you look on the block, you will see a cord coming out of one of the freeze plugs. that will tell you if you have one. if you do look around the drivers front (top) you will see a cord wound up. If you cant locate it ask the dealer and they will show you, some people run it through the grille, you might want to look there was well. not all Escape came with one