Provided you are talking about the MIL Light = Malfunction Indicator Lamp? the 97 Mark VIII is an OBDII computer system. it requires a scan tool to reset / turn off the MIL / check engine light. it requires repairing the fault / problem to keep it off. drl
There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.
The "Check Engine" light means that the computer has stored a fault code. You need to use a code scanner to read the fault code. Code scanners can be borrowed, rented or purchased at most auto parts retail stores.
You have to check to see what codes are causing the check engine light to be flickering etc. that will be your starting point. Sounds like oxygen sensors though. the spark plug boots are cracked my 98 had the same problem $3.80 each
If you don't have a scanner take it to Auto Zone or I think even Advantage does it and they will tell you what the code is and erase the code for you.
Disconnect the battery for a few minutes and then connect, resets other things too.
press the reset button
Check Crank sensor located in the block near the ac compressor
See if the button in the door jam is stuck and put WD-40 on it and work it in and out, and of course check the light bulb.
Check the basics, With an inline spark tester ($6-8.00) check for spark. Does the fuel pump make noise when you turn the key (whining noise)? Is the fuel getting to the engine?
1st. Push the compass and reset button at the same time. 2nd. Select "reset" to reset the compass. 3rd. Start driving slowly in a circle, until it resets.
In the trunk there is a trap door on the drivers side with the on off button.
Disconnect the battery for about a half an hour then re connect.