Its a bit of a job because it is held on by the same bolts as the intake manifold, and the easiest way is to remove them both, otherwise the rusted exhaust bolts holding the tubing to the manifold is the worst.
Intake manifold delivers the fuel air mixture to the cylinder heads, exhaust manifold collects the gases after combustion, and channels them into the exhaust pipe.
It sounds like you either have a leak at the exhaust manifold or the intake manifold. Most likely is the exhaust.
You have to remove the cross over section of the exhaust
It is easier to remove the upper intake.
In a 1998 Jeep Wrangler, the oxygen sensor is located in the exhaust pipe. It can be found just below the junction of the exhaust manifold and the exhaust pipe.
in the catalyc converter... exhaust manifold
normally they are located on the exhaust. you may have three. on the manifold and on the exhaust pipe itself...
the oxygen sensor is on the exhaust manifold directly in front of the fan. there is one above and below the manifold.
You can find it in the exhaust manifold.
the O2 Sensor Should be on top of your exhaust manifold
Two on each exhaust manifold. Remove the engine shroud from the cab area and you should be able to get a both very easily.