I would remove the switch and hook a test gauge to check for actual pressure, but it is common to have cheap sending units. As for breakfastboy it sounds like you have a partial clogged oilpickup screen.

 

Any suggestions on cleaning that capricorn? Do I need to drop the oil pan etc?? I have the 4x4 and hear that it's a pain to do that.

 

Sorry I'm taking so long to reply breakfastboy but yeah, it will require the oil pan to be removed and you will have to jack the motor up off the mounts. It's a little bit of a pain. Get some studs (4) and put on each corner of the pan rail to line up the gasket and pan then start some bolts. Remove the studs and replace with bolts.