Oil pump issues ?

Hi I am looking for some advice on the following. I have a 1996 4 cyl 2.0 Contour standard, and always change oil & filter myself. This time when removing the filter I noticed there was hardly any oil in it always been full before. Fitted new filter and put in 4.5 quarts of new oil. Dipstick showed oil up to the top v mark on dipstick. Ran engine now dipstick shows oil at the bottom of the lower v mark. Whats going on, where is the oil going. There are no leaks. The car drives as normal as before I noticed this. Could I have an oil pump problem. Could the pump have lost its prime. Would appreciate anyones input on this.
Regards Steve R

You've got questions. Contour.org has answers.

A guy asked this same question the other day regarding the V6.
http://www.contour.org/ceg-vb/showthread.php?t=18226