Have an 05 pacifica with 3.5.new oil pressure switch ,odd results. start the engine the oil light comes on, shut it off wait about 30 seconds restart and the light goes off. This is not intermitent!

I am not familiar with the model so I am not aware of any quirks it might have.

It has to be assumed the oil light is telling the truth and there is in fact little or no oil pressure on initial start up.
An oil switch doesn't put the light on at zero pressure but whenever the pressure falls below whatever the minimum rating of the specified switch happens to be - the lowest I have encountered is 4lb and others have been as high as 12lb sq in.

I have encountered similar problems before and on all occasions except two it was caused by oil drain back - due to time and gravity the oil in the lubrication system would drain back into the oil pan causing a "dry start".
The causes for this have variously been a low oil level, an excessively worn oil pump, a fractured or displaced oil suction pipe or the wrong oil filter. This refers to the canister type or spin-on filter, some of which contained a valve to prevent drain back. The valve wasn't incorporated into the offerings of many aftermarket suppliers.

The other two instances were caused by a partial blockage of the suction pipe gauze filter by the collapse or pushing up of the steel oil pan after being heavily grounded.