Will be bringing home my very first beauty queen, a 1998 Grand Marquis LS. She is Silver, 4.6, all options, and only 118K miles. I will be getting her for only $800, due to the current owner transferring across the country and unable to take her with them.

I would like to ask hat you folks think is the best plugs to put in that 4.6?

 

Hello, and welcome to the Mercury Forums !!
Modern spark plug technology has advanced greatly since your '98 Merc was built -- the original "double platinum" spark plug specifications no longer apply.
After several years of experience and thousands of miles of driving under extreme conditions, I have found the best-performing, longest-lasting spark plugs to be the BOSCH brand.
The 95 MERC 4.6-liter SOHC engine calls for the "Bosch # 9605" used with the early "Ignition Wires"-- a DOUBLE-IRIDIUM design that gives excellent performance and maximum electrode life.

The recommended plug for your "coil-on-plug" '98 Merc is the BOSCH # 9606 -- Amazon.com has 'em for a good price.