I checked the codes on my 2000 dodge and get a P0336 fault(crank shaft position sensor).Can you tell me what that does and can I replace it.My tach sometimes falls to 0 when the truck is running.It has no power when this happens.Its also hard to start sometimes.Could these things be caused by my new foun fault?Thanks for your time.

it senses engine position and rpm.
You can replace it, although you may (will) have to remove the starter to get at it.

Your tach and low power complaints can definitely be caused by a bad crank position sensor

dogwood sales, did you ever figure problem out with the Crank Sensor? My truck has problems starting and I think I've narrowed it down to this