If you dont know how to replace spark plugs I recomend you go to someone that does and have him show you because you might do more bad then good trying to change them for the first time.
All depends on what kind of spark plugs you have. It could either be 30,000 miles or 150,000 miles.
You don't. The gap is not adjustable.
You can remove the spark plugs in your 2003 Mitsubishi Eclipse by turning the spark plugs to the left. You should use a 5/8 deep well socket. The spark plugs will come out.
Every 30,000 miles except platinum plugs
The left side of the motor.
Once on 1-2 year on regular spark plugs. Once every there years on High end spark plugs.
if its a four cylinder it has four if its a v6 it has six a spark plug per cylinder
Firing order is 1342 - spark plugs order is 1234 from left to right
4 cylinder has 4 6 cylinder has 6
three are on the front valve cover the other three are under the intake manifold
It could just be a bad spark plug wire or the spark plugs need changing.
Replacing spark plugs is pretty simple. Disconnect the battery, remove the cover and cables, remove the old spark plugs, put in the new spark plugs, put the cover and wires back on the spark plugs, and reconnect the battery.