You need to take it to a Ford dealership with service department, they can then put your vehicle on a machine that they hook up to your vacuum system and pump smoke through it to find the leak. Usually cost like $100.00
Get a vacuum diagram from MOTORLIT.COM
I guarentee its a vacuum leak... i had a 1997 sable 174 and 171 all the time turned out to be a vacuum line
towing capacity of 2003 merc. sable is #1000 class 1 hitch
The ( 1997 ) Mercury Sable Owner Guide shows , for all models ( 60.6 liters / 16.0 U.S. gallons )
Mercury Sable was created in 1986.
All 1998 Mercury Sable vehicles have a ( 16.0 U.S. gallon fuel tank ) * according to the owners manual *
check pcv hose elbow for vacuum leak.
A 1998 Mercury Sable ( all vehicles ) have a ( 16.0 U.S. gallon fuel tank ) according to the owner manual
Any vacuum line connected to the plenum.
set to desired station hold button for approx. 3-5 sec. until station flashes
how do I remove my air bag from my mercury sable