check pcv hose elbow for vacuum leak.
The 1995 Mercury Sable would have come from the factory with ( 5W-30 ) oil in the engines
Could be a bad inertia switch.
how much would it cost on a 2004 mercury sable
On a 2000 Mercury Sable : The automatic transaxle ( transmission ) fluid level dipstick would be near the firewall just to the drivers side of the engine ( where the transaxle is bolted to the engine )
Possibly the Head Gasket is blown.
Replace your transmission pump or get a new transmission.
According to the 2002 Mercury Sable Owner Guide : ( the 6 disc C.D. changer is either located in the center console , the trunk , or the right side of the cargo area , that would be for the wagon version )
It stalls even when warm
check all your ground wires
Fuel leak at hose or fitting Carbon canister is exhausted
The first clue would be if the car doesn't turn over :)
The stalling could be caused by several things. The egr valve could be clogged, or there could be a sensor problem among other things. Clean the egr valve first, then check the computer codes for possible problems.