stang wont crank over..HELP!!

[IXCELR8]

94 gt, aode. About 2 weeks ago I parked my car at the mall and went in. Went to leave and nothing!!..it just clicked, towed it home and proceed to replace the starter, new starter in and still nothing!!. I was having problems with the TR sensor after I pulled the tranny to replace a leaky rear main seal but usually I could give the shifter a knock and it wold be fine. Is there a way to test the TR sensor other than replacing it, I did end up putting a new one in. I had my old starter tested and it was fine. The weird thing is sometimes it will start no reasoning to it and no set pattern. Any suggestions??...