Unfournately, those are signs that your engine is worn and will need to be rebuilt, or replaced. Those are signs of worn rings your probably getting little or no compression.
There are several things that can cause your 2000 Mercury Mountaineer from running. The most common cause is a lack of fuel. You might want to start by changing your fuel filter.
Remove the gas cap, then look for a Schrader valve on the fuel rail. If it has one release the pressure there. If it has none, then wrap a rag around the fuel filter coupling and prepare for a spray of fuel when you disconnect the fuel line from the fuel filter.
On a 1997 Mercury Mountaineer : I assume the fuel filter would be in the same location as a 1997 Ford Explorer : ( underneath the Mountaineer , below the drivers door , mounted on the frame rail )
On a 2001 Mercury Mountaineer : Underneath the Mountaineer , below the drivers door , mounted on the frame rail
02 sensor or cat
On a 2001 Mercury Mountaineer : The fuel filter is under the vehicle , below the drivers door , mounted on the frame rail
Blocked fuel filter or failing fuel pump. Autozone will test fuel line pressure for free. If fuel line pressure is low, replace filter first.
It didn't come with a cabin filter.
Inside the transmission. Pan must be removed to access the filter.
It has a vacuum leak somewhere.
In the car Duhhh..
it doesn't have one