Temperature gauge ??

[Lt. Clang]

Hello, Clang here.
Hey, I hope someone can help me. On my 1997 Trans sport, the temp. gauge works great and then pegs. I wiggle the wires under the hood running along the front of engine bay and then it works for awhile. I am figuring that I have a loose wire or bad connection. Here is the dumb question. Where is the sending unit that goes to the gauge? What color wire is it? Thanks!!
LT. Clang.