What happens if I remove the wire to the TCC solenoid?

The car only does this when we slow down to stop. (more often after we have gotten off the highway) It starts vibrating, shaking, ect really bad, then dies once we have almost come to a complete stop, and the brake petal gets hard to push. Then we try to start it, it runs, until we put it into gear, then it dies again. Once we have let it sit for awhile, it will go again.
Like I said we took it into a dealer repair shop and they said it was a bad TCC solenoid, and would cost the over $600 to replace the solenoid.
After reading the internet it shows that the part can be replaced just by removing the transmission pan. The dealer says that they have to remove engine bolts, the transmission, ect to get to it. We dont want to try to fix it ourselves until we know where it is exactly. I have not been able to find that info out just yet.
I did read that you can simply unhook the wire to the solenoid, but it would cause the car to use more gasoline.
Is there anyway to find out for sure where that is located? We have a book on the car, but it does not show the location.
If I add that seafoam cleaner, do it matter how much I use for my car? It wont hurt adding it if the fluid is already full?
I would like to try something like that first. Then if that doesnt work, I could try unhooking the wire to the solenoid. My car has over 204.000 miles, so its not like it has long to live anyway. But then I have seen several sunbirds at Pull A Part that have at least 250.000 on them.
I just didnt want to unhook it and have it cause more problems.
Thanks again, JR