On my 97 PA when the engine is running, if I remove the oil filler cap there is a noticeable vacuum and then the engine runs rougher. I put the cap back on an she is running prefect. Is this normal?

Also, where is the PCV located on this engine?

Thanks!

The "vacuum" is an indication that your PCV is working as intended. If you want to know where it is and how to change it; Click Here (http://www.automotiveforums.com/vbulletin/showthread.php?t=658738)

There should be a slight vacuum in the crankcase. I don't believe it should run rough when the cap is removed. I'd change the PCV valve & check the condition of any O rings.

There is a good vacuum suction when you go to pull the oil cap off. It is not really sublte vacuum.