stalling and cutting off!!!!

I Have A 2001 Dodge Intrepid And The Other Day It Cut Off On Me Out Of Nowhere....I Checked The Oil And It Was Completely Empty...and I Just Recently Had An Oil Change. I Took It To Auto Zone Bc The Check Engine Light Came On Soon After...The Guy Hooked It Up To The Machine And It Read Barametric Pressure Is Low...He Couldnt Tell Me What That Means Bc He Didnt Know...Might Wanna Find Another Job!! So Can Somebody Please Tell Me What That Means And What Does It HAVE To Do With My Car Cutting Off On Me... What Do Have To Do To Fix The Problem?

Lets start with the oil pressure did it drop before the problem. Were you down 5 quarts,4 quarts or 3 quarts. I would go to the quick change place and complain. If you were down 5 quart your looking at a rebuilt engine. Does it knock at this time full of oil. Was the drain plug out of the engine? This would mean it wasn't tightened at the oil change. Was their two gaskets on the filter.
This problem needs fixed before going any further.