Broken rear manifold stud. What problems should i expect?

[Sfarring]

I just bought 97 Wrangler 4.0L. I've noticed the idle starts creeping up as it gets warm. I started poking around at the normal things and as I'm inspecting the intake manifold I notice the rear most bolt/stud is missing. I stick a screwdriver in the hole and there is definitely something blocking it, so I assume the stud is broken. The exhaust manifold looks newer and I'm guessing it was broken at that time.

I know how much of a bear it can be to fix this, so how big of an issue is it to leave?

 

[nathanotis]

Extracting a broken bolt can be easy, or it can take hours. You never know til you doing it.

Were it me, I'd pull the manifold and check it with a straight edge. If it's flat, slap a new gasket on, chase the threads (ie: clean them up) and replace all the mounting hardware with new. Torque it to spec and be on your way.

If it's got a warp to it, find an exhaust shop to flatten it (assuming there's a good amount of meat left on the flange) or get a new manifold.