my car is a 1990 automatic transmission i dont know if is the same type, but try to check the two switchs in the back of brake pedal, (i have two) (stop ligth & cruise control), and/or remove the (RND12) cover and you see a "mechanic switch" check the cables connections and the signal (you will need a ohm/volt meter).
i think that your trany is good maybe is the switch...
well maybe this help
and i hate when people said "GET A MANUAL transmission" some of us love automatic...
p.s. sorry for my english..... :p