First you must remove the plastic cover on top of the engine. the spark plugs are located directly under the coil packs and there are no plug wires so when you remove the coil, you will see the top of the plugs. This is not too difficult even for a shade tree kinda guy.
8 spark plugs
8 spark plugs
Remove the spark plug wires from your 2002 Mercury Grand Marquis spark plugs. Remove the spark plugs by turning them to the left with a deep well 5/8 socket. Reverse the process to install the new spark plugs.
Under the coil on each cyl.
According to one of Fords websites : For a 1993 Mercury Grand Marquis , 4.6 liter V8 engine : ( the spark plugs are gapped at .054 inch )
there is a coil on each one. remove the coil and there is the plug.
Each spark plug has a coil on the top. Just remove the coil.
The original plugs should be good for around 100,000 miles ( 160,000 ) kms. Take it from there.
remove engine cover
Intake manifold gaskets are leaking, intake manifold is warped.
Have you checked the coil's ?
Depends on which shop you take it to. Usually around $350 for plugs and wires, etc.