I get a code po 336 which is crankshaft sensor , how many crank shaft senors are are on a 2001 montana

The CMP sensor is located somewhere on the head. Usually means either you need to replace the main seal or more likely your timing is off and you need to replace your timing belt or chain.

Possible that the teeth the sensor reads got something on them and is causing problem but most common problem when eng has not been in to is a bad wire conection at sensor or in harness damage. Best to check the volts in and out at sensor and confirm continuous read then do continuity test on wires between sensor and ign module.

304 is misfire on cylinder #4. #4 is the middle cylinder on the driver's side.
The other 2 relate to the crankshaft sensor:

P0335 Crankshaft position (CKP) sensor -

possible causes: circuit malfunction Wiring, CKP sensor, ECM

P0336 Crankshaft position (CKP) sensor - range/performance problem
possible causes: insecure sensor/rotor, air gap, wiring, CKP sensor

Is the car running? If yes, check for a loose connector on the crank sensor. You may need to take the connector off and see if there is any corrosion on the terminals. If yes, do your best to clean with a small screwdriver and/or electrical parts cleaner.

From what I can tell, the sensor is on the bottom of the engine near the idler arm, but it has a long pigtail such that the connector is on top of the engine by the fuel rail. See pictures below.

for the misfire,

Please see my tip at http://www.fixya.com/cars/r6715318-causes_gasoline_engine_misfires . These are generic instructions. If you get stuck or need specific instructions for your car, please get back to me with model, year and engine info.

this car does not have a camshaft sensor the distributor pick up coil acts as a cam sensor here is crank sensor info the crank sensor is located in front of engine just behind the crankshaft pulley using ohmmeter check resistance between terminals on sensor replace is not within specs cold 1630-2740 ohms hot 2065-3225 ohms if this is not the problem please reply to your post ill monitor it. hope this helps

i would say either a temperature sensor or mass air flow sensor.

If all the fuses are good,replace the crank shaft sensor,this is the problem.

It should be down near the crankshaft pulley. Remove the the right front wheel and the splash shield, it should be there next to the pulley.

down by your crank shaft pulley you will find a sensor with 2 wires ruining into it and 1 bolt holding the sensor in remove the bolt and twist and pull on the sensor then slide the new sensor in then reinstall bolt and wire

First be sure it is the crankshaft sensor. by getting a trouble code. at Autozone or other store.
The crankshaft sensor is usually located near the timing belt cover. If not , it can be inside the cover in some cars. No, the ECU will recognize the sensor . There is no need to move the timing. If there is any trouble after installing a new sensor.
With the key turnd off, remove the negative cable and reinstall it after a minute.

The crank sensor is a well known cause of no spark condition, it is most likely the real problem, the crankshaft sensor for a Jeep 2001 is located behind the starter, you have to remove the starter to gain access, even then it is hard to get at.