2000 Jimmy

My Jimmy has decided to go to hell..o... It has been suffering from an issue where it would occasionally lose power, just sputter and lose idle, but rarely. Now that it has been hot here, today with the air conditioner on it acted like it was going to fall apart all together, absolutely no power at all. I need help, I have a mechanic abbout 100 miles away who will fix everything and charge 1/2 for labor but i need to know so i can get the parts because he cant make me a deal on parts, as well he cant quote me for repairs without an idea what is wrong and I would like to have a generic idea.... help

Anyone know a reliable and inexpensive place to get a used TCCM (Transfer Case Control Module) for my 2000 GMC JIMMY. I notice a clicking sound coming from it everytime the service 4wd light flicked on and off and I am assuming it is the issue since it was trying to change in and out of 4wd even with everything else disconnected.

So if anyone knows where i can get one let me know.