what woulke fliud in coil pack
You never want to wash a Triton engine. Condensation also plays heck with these coils but if you can do it yourself they are cheap to replace.
If it is water then don't wash the engine, use some compressed air to remove the liquid. If it is oil then the cam cover gasket needs to be replaced. If you have a bad coil make sure you replace it with a genuine Ford part as the aftermarket parts seem to be hit or miss. If the car has over 100,000 miles on it I would replace all 8 coils if you are having issues with miss-fires or rough running engine.
I have had excellent luck with aftermarket coils I bought from NAPA. Not NAPA brand and they have a lasted for years.
Looking for a Used Grand Marquis in your area?
CarGurus has 2,247 nationwide Grand Marquis listings starting at $1,500.
Search Mercury Grand Marquis Questions
Mercury Grand Marquis Experts