Thanks for using Just Answer. I will be glad to assist you.
What size engine do you have?
Good news!! I don't believe that you're having a head gasket problem.
I believe that your issue is with the coolant temperature sending unit for the gauge. The sensor sends the information to the gauge to display the coolant temperature.
There is a technical service bulletin issued by Ford for your vehicle because of defective coolant temperature sending units. A new part has been created and it should be replaced. Please refer to the TSB information below:
Article No. 95-13-2
LINCOLN-MERCURY: 1981-92 TOWN CAR1981-95 COUGAR1983-95 GRAND MARQUIS1984-92 MARK VII1984-94 TOPAZ1986-95 SABLE1987-89 TRACER1991-94 TRACER1993-95 MARK VIII
LIGHT TRUCK: 1982-95 BRONCO1983-95 RANGER1986-94 AEROSTAR1990-95 F-150-350 SERIES1991-95 EXPLORER1992-95 ECONOLINE1995 WINDSTAR
ISSUE: Temperature Sender F1SZ-10884-A with a build date code prior to 2774 (277th day of 1994) should be purged from your inventory and returned to your facing PDC. These parts are being made obsolete because of an incorrect crimp during assembly. Installing these parts on a vehicle could result in early loss of temperature sender function.
ACTION: Remove and return the suspect parts from your dealership's inventory. The obsolete parts should be withdrawn from your inventory and returned to your facing PDC within 30 days of this TSB.
NOTE : USE TSB ARTICLE 93-24-8 FOR DIAGNOSIS PROCEDURE IN DETERMINING IF LOW GAUGE READINGS COULD BE ASSOCIATED WITH A TEMPERATURE SENDER CONCERN.
Credit for parts and prepaid freight costs will be issued.
Replacement stock is available for ordering
OTHER APPLICABLE ARTICLES: 93-24-8
WARRANTY STATUS: INFORMATION ONLY
OASIS CODES: 203000, 203200, 204000, 204200, 402000
Here is the inspection procedure to test the coolant temperature sending unit: