Heater core replacement 95 mercury mystique 2.0

SOURCE: firing order of mercury mystique

What engine size and year?

SOURCE: mercury mystique starter location

its a 6 I beleive its a 2.5

SOURCE: replace heater core 1995 Mercury Villager

Unfortunately, this is one of the most complex and time consuming operations, short of changing the engine/transmission that can be done to the car.
The heater core is mounted in a box, inside the passenger compartment, almost dead center behind the dashboard and is mounted directly on the firewall to allow the hoses to go through. If you put your hand just above the accellerator pedal, and go toward the center console, you'll find the heater core box.
There is no way to remove the heater core from the engine compartment. In fact, other than draining the radiator and removing the hose clamps and a bolt or two, youll have little interaction with the engine compartment.
Begin by disabling the air bag system, by removing all power from the vehicle. Be SURE the air bags are disabled as they are extremely dangerous if they activate while you are working under the dash.
Next remove the entire instrument panel, and all the decorative plastic. To do this you may have to remove the steering wheel also. Be sure to label everything as you go. Then remove all the heater controls. Once done, you should be able to access the black heater box that the core rests in. Remove that, and if you have loosened the hoses and screws in the engine compartment, the heater core will come free and you can replace it.
For a much better and more detailed explanation of how to do this, I used the Haynes Repair Manual. (Note, Im not affiliated with them, they just had the best description of the procedure.)
I dont really recommend doing this yourself unless you are a very patient and reasonably accomplished mechanic. This will involve removal of all the dash, instruments and controls, and frankly, even when the dealer did this, the car is never quite the same again.
One other hint, after replacing the heater core, use a length of good heavy copper wire to wrap around one of the hose entry points (metal to metal contact) and then ground the core to the engine block or frame. This will help prevent the electrolysis that killed the core the in the first place.

SOURCE: is it difficult to replace the heater core in a 97

It's time consuming. you have to drop the whole dashboard and steering colum in order to get to the heater core. In a scale of 1-10 with 10 being the hardest, i say it's an 8.

SOURCE: 1995 mercury mystique starter replacement process?

At first, it looks like an impossible task, however if you start by removing the positive battery cable, then unplug mass air flow sensor, carefully remove air filter box and its components from the throttle body. from there you should be able to see the starter better and have more room to work and get it out. You can take the battery right out if you want a little more working space for your elbows. take the wires off the solenoid, sometimes the old studs of solenoid will break due to corrosion. remove the two 13mm bolts that hold the startersome models have one at the bottom also that you will need to access from the bottom side.