1998 Ford Contour cng low miles

1998 Ford Contour factory bifuel cng-gasoline. 4 cyl, auto, cold air, tilt, cruise, stereo, 73,843 actual miles, good tires and interior. Dark tint glass. Spot on roof where paint has come off shown in photo. Runs perfect on gasoline and runs good on cng but does have an irregular idle where it idles too slow sometimes and turns on check engine light on cng. It is still driveable on cng and runs down the road well on cng. Price is reflecting these defects.