92 Bonneville--Please help

This may be a stupid question, but I could really use a bit of help. My girlfriend's 92 Bonneville has been having some transmission problems. The transmission was replaced ~30k miles ago, so I ruled that out quickly. The problem seems to be the metal tubes that bring the transmission fluid into the radiator to cool it (at least I assume that's the purpose of it). My problem is that I have no idea what the actual name of these tubes are, so it is making it very difficult to search for them and get some prices. Any help is greatly appreciated.
Also, since I'm asking, might as well see if my assumptions are correct. The transmission seems to have problems shifting, although if you let off the gas a bit, then give it gas again, it seems to aid in the shifting. Could these tubes I was talking about (they are rusty and corroded) be the cause of this problem? I'm hoping they are since they don't seem to difficult to replace and probably wouldn't be too bad of a hit on the wallet. Thanks in advance for any help.

The tubes are just called transmission coolant lines. As for the shifting problem it sounds like you have a problem with the vacuum modulator. It is located on top of the transmission. It is not hard to change, just unbolt it and reach in with a magnet and remove the oriface. Put the new on and your problem should shift much better.

Hmm, guess I'll have to check that also. I just kind of assumed it was the coolant lines since when I felt them, they were rusty and had some transmission fluid on them (it's been leaking badly). Maybe I'll just replace both then and hope that works. Thank you very much for the response.

I can't seem to find the coolant lines on any websites. Anyone know of some really good websites for auto parts?