You don't. Unhook the battery for a minute. That will reset it.
Check the codes with an OBD2 scan tool.
The OBD-1 diagnostic connector is located on the back of the block beside the starter. A series of jumper wire locations are used in conjunction with watching the CHECK ENGINE light.
In the 1997 Mercury Villager, the Transmission fluid dipstick is located on the driver's side of the engine just in front of and below the master cylinder/brake fluid check. The 97 Villager has a bulbous knob on top with no indication that it is the Transmission fluid.
dash dash
we need to know what year, model, and which 3.0 you have, there were more than one.
There is really no method to "check" the resistor, text by substitution.
Timing is set by the PCM and is not adjustable.
Check the Mercury Villager manual to see if there is a special procedure for cleaning the fuel injector. If not, you can purchase cleaner. You can also have the injectors cleaned by a mechanic or an oil change company.
Check tire pressures and rebalance tires first.
have vehicle scanned to determine problem
The easiest way is to unhook the battery for a minute.
You'll need to install a tee into the line by the fuel filter to check it, there is no shrader valve.