You really have two of them. The first one is leading from the headers into the exhaust pipe. Get below you Jeep and start looking in the general area under the driver's door. You should see a sensor sticking into the pipe with a wire at the end. I just got under the 92 I own and see the 4 wires going to an insert, screwed into the exhaust pipe just after the two parts of the exhaust maniofold join.
It does not have a mass airflow sensor.
It is located at the driver's fender side of the the throttle body.
If you browse this website you will be able to find what you need: http://www.jeep4x4center.com/mopar/jeep-grand-cherokee/backup-parking-sensor.htm
I had that same exact problem with a 1995 Jeep Cherokee, and it was indeed a bad oxygen sensor. Relatively cheap repair too.
It is located on the passenger side of the motor after the catalytic converter. The cat is at the end of the exhaust manifold, so the connector is accessible at the motor, the sensor is accessible from underneath the car.
Need a special socket. They are located in the exaust manifold(s).
It does not have a mass airflow sensor.
It is inside the distributor.
The oil sensor is located above the oil filter next to the distributor.
above the filter
Inside the distributor.
The cam sensor is inside the distributor.
The 1994 Jeep Grand Cherokee IAT sensor can be found attached to the air intake hose. The IAT sensor will be near the air filter box.
It is in the distributor.
in a toilet
It is the two wire sensor next to the thermostat housing.
The cam sensor should be located underneathe your distributor cap. That is the placement on my 98 Grand Cherokee and it should be located there as well on yours.