1997 Mercury Marquis Marquis with codes P0171, P0174, P1131 &

Engine Performance problem
1997 Mercury Marquis 6 cyl Automatic 94000 miles

Car runs rough at idle, difficult to stay running, MIL on, once at high speed runs pretty good except stutter (?) At 30mph and 60 mph. Needs to pass emissions and trying to decipher what to fix. Any help is certainly appreciated.