Where is cylinder 3 on a 2004 pacifica - 2004 Chrysler Sebring

The camshaft position sensor is always located near the camshaft, often at the top of the valve cover, but it can also be installed from the side of the cylinder head.
Check around the head or valve cover and follow any electrical wires and you will for sure find the camshaft position sensor.

https://www.2carpros.com/articles/camshaft-angle-sensor-replacement

https://www.moparpartsgiant.com/oem-chrysler-pacifica-camshaft_position_sensor.html

Post a picture.

cylinder # 4 is the middle of the forward facing head(radiator side)also known as bank 2 which is cylinders 2,4,6 the back head (bank 1) is cylinders 1,3,5

We have had those for 35 years

So nothing new there

Read your owners manual

If it flashes- I would not be using it -as it could
be a Class A cylinder misfire, that could ruin your
exhaust converters

Check your OBD Codes

6 cylinder is 153624. 4 cylinder is 1432.

Go to the auto parts store and get a tester that fits on the spark plug and on the spark plug coil and it will flash if the plug is firing.You could use a inferred thermometer and aim at the exhaust header and the cold spot is the cylinder not firing. Number 4 is the cylinder in the middle by the radiator side

here ya go

look at your oil filer cap and if its milky looking then its possibly your cylinder head gascet

Look under the hood and either on the right or left side near the firewall will be the master brake cylinder. There should be a screw cap for the brake fluid, put it in there to the FILL line. DOT3 fluid probably.

Your Pacifica 2004 has a 3.5L engine 6 cylinder, you will need six spark plug's, the spark plug gap is .050", make sure you gap the spark plug's before you install them, hope this was very helpful.