Boot Sensor?

I brought my 96 Ford Probe in for inspection and they told me I had four computer errors. I recently been having problems with my car stalling on me as if it were acting like it were out of gas. They told me that the Boot Sensor needed to be replaced (a $500 part). The shop, Courtsy Ford told me that it would fix the stalling issue and rid me of at least one computer error but they were unsure if it would clean up the other three. My question is, what exactly is a boot sensor and what does it do? Could it possibly be causing other errors? Is there somewhere I could order the part for cheap and have them install it? I just bought the car a couple months ago for $3800 with 89,000 miles. The mechanic that checked it out told me it was in great shape, but I've already spent $1000 in repairs in replacing rear strut bars, breaks, front right cv joint and repairing several other minor things. The car ran perfect for the first month and then all of a sudden shit hits the fan and all these problems are arising. They also found out apparently there is some crack in my front windshield which I'm hoping I have insurance on and that will most likely cover it. I'm kind of in a delema on what to do with the car, I don't know if I should dump more money into it. I'm afraid if I fix the boot sensor I will still have three other errors that I may need to put more money into. I really love the car besides all the problems, It's got a nice fancy body kit and was just kind of hoping that after fixing all these problems it would be fine. It idles very nicely without hiccups untill recently. Please give me your opinions, I'm lost!
Thanks guys!!