Well, you can remove the broken parts of the cable and take it to a bicyle shop or such and they can likely make you up a new one for $10 or less. A complete new IMRC is rather expensive. You still likely need to clean the intake since the cause of the breakage is normally stress on the cable due to crude building up and making it not want to shift the butterflies easily.
But if you are not in a very cold place, the cheap (zero cost) and easy way to handle this taking less time than anything else as well, is just to wire the butterflies open and take the entire IMRC out of the operation, regardless of its condition. What it does is open those butterflies, nothing else. A fair amount of testing by people on this board and on the other main V8 SHO board has indicated just having them open all the time causes no problems of any note except in extreme cold starting.
To wire them open, just find the end of the cable and pull it to see where the spring and arm are at that the IMRC actuates. Then, using wire or strong tie wraps (I just used tie wraps) pull the arm to full open and then wire it down in that position to some near by chunk that does not move or get hot enough to melt things. It took me about 10 minutes including getting tools and such, and I did it alone, which is a hassle since you really need 3 hands. If you can get someone to hold the arm in the open position for you while you wire it down, you can do it in half the time and then never think about the IMRC again.
pax, smn