I've never changed one on a YJ but on an XJ I did (an '87-'90) and it was a breeze. You don't need to disconnect everything on the intake manifold like the manual says. I just undid the 14 bolts that hold the intake and exaust manifolds in place and was able to pull the intake manifold about 4 inches off the block, just enough room to clear putting in the new exaust manifold (I did headers). The only hard part, and this was on an '88, was the EGR tube, the bolt onto the exaust manifold is a PAIN to get to. Other than that it's pretty simple, good luck.
"Nitrous? So is that like viagra for your Jeep?" -mom
"I flopped it"