Side Brake Lights not working, third brake light still is...any ideas?

Last Friday, a friend of mine went to get an inspection sticker for my 2001 GT...upon showing up there, he was informed that only the third brake light was working. He left the garage and trouble shot the problem for a while...no luck...he drops the car back off to me...all three are working again. Then yesterday, the two side brake lights went out again. I called Ford and spoke to a shop foreman who helped guide me a bit... I was informed that the 3rd brake light runs off a seperate switch. However, I tested both switches and both are working fine. The fuses and grounds also appear to be all set as well. I read through some of the posts on here, but still haven't been able to solve the issue. Also, after reading the posts, i realized that my cruise control is not working, as others have mentioned. Any ideas as to what would cause this and/or how to fix it? Thanks in advance,

all of the lights besides the two side brake lights are working properly. ill check the multifunction switch later tonight...i also spoke with the ford foreman who said that it is mostlikely the switch and ill probably need a new one since they are known to go after a number of years.

so i went to ford today and picked up the new multfunction switch...installed it...thats not the problem. then we decided to try to narrow down where the issue was. tested the entire tail light, everything is getting power, even the brake light wire... right now i know its after the switch on the pedal and before the lights...and i have no idea where to look. also, somewhere during the proding, between checking the left tail light, dropping the fuse box, and putting the old multifunction switch in, the back left blinker stopped working. i am completely baffled as to where else to look...not only for the brake lights, but now, the rear blinker as well. any ideas would be greatly appreciated.

also, i took off the left tail light and plugged the entire light into the right light's socket...both blubs are working fine and the blinkers on that side worked, so it is not the filaments. all the other lights are still working fine on the car, including the front left directional. if i had done something with the fusebox, i would expect either the entire left side not to work, or both directionals to fail. i was assuming that it was something with the contacts, but since all the other lights are working fine, im not entirely sure what could cause this,.