I am currently trying to determine if and where my possible vacuum leak is. Have a lean read from my 2 new O2 sensors when the temp is cold and when not at operating temp-Front and Rear O2 sensors not switching, system is or was lean. Codes 172 and 176!

Have researching this problem and it seems quite a problem for our cars! Need to take 'er South.

1995 Mercury Mystique LS OBD1 2.5 L Duratec ATX- No modifications 70,000 Miles w/ O.E. Water Pump or Replaced: VSS, Lower speedo-cable(2X) Use: Mobil 1 5w30 and Techron Fuel Treatment.;) and Mobil 1 ATF Change every 10,000 miles