91 and newer has the High Output 4.0 EFI engine. The 87-90 4.0 used in cherokee's runs a renix system. IAT is needed to run a good, true, closed loop system. I'm not 100% sure if yours has one, but I'm guessing it does. Look for a sensor on the air box or a sensor on the manifold. If you think you found it, pull it out and eyeball it, Get a good feel for how deep it goes. If it is deep enough to be in the air stream, it's probably an IAT.