Gorgeous car! The check engine light IS a smoking gun. Chain parts stores will pull codes for you. Use that info and the internet as your friend. It may be a simple vacuum leak as these are common at the large rubber pipe that exits the intake manifold, top of the motor, passenger side. Try to alleviate the issue before you give her away. You are among a huge collection of extremely smart guys and together we can save your baby.
'04 Silver Marauder w/ sunroof - HID lighting, JL Audio / Eclipse DVD/NAV/iPod/camera, 4.10's, 2" drop, Progard Bumper Baffle, Delete tips, Billet Pedals, BC4E dead pedal, Lidio Tune, Mach1 chin spoiler, K&N CAI, TCE lines, Super40's, tinted tails, SS Inserts, Heinous Control Arms, Real oil gauge, lighted door handles. Currently installing Eaton M112.
2004 Mercury Marauder
Born March 2004, adopted October 2005. Sold January 2012, adopted AGAIN January 2016
2,187 of 3,214
997 in Silver Birch
448 with light flint interior
304 with heated seats
336 with sunroof