my wifes 2004 dodge stratus with a 2.7 has a problem .....

If your car has plenty of oil in it and its running the same i would air on the safe side and have the oil preassure switch changed out and any other oil realted warning devices see what happens and go from there. If the car was mine thats what i woul do honestly rather than try to hook gauges up an take readings and all that bull shit and i say this cause yes it will cost money to do either one so why not just switch the part out and forget the testing once u have new parts if it still does it u know something else is up and u did not waste that money for nothing at least u got some new parts out of the deal and u end up with the same info kind of a tough one to answer but thats proll what id try on my own vehicle first and find out were the part is located maybe u can change it if u think u can email me ill send some tips your way once you tell me where it is if things get this far then sell that car they have lots of issues go out and get a Honda or toyota and never ever have a problem like that again its usually just maitnence with those makes take good care of them and they will do the same for u