I just replaced a set of Motorcraft, AGSF32FM with 64,000 miles. I bought them from the dealer who claimed they were 100,000 mile plugs.

All ground electrodes were extremely worn and 2 plugs had most of the center electrode gone.

I doubt these plugs are even 50,000 mile plugs. No more fine wire plugs for me.

I also switched the air cleaner. I had put in a Fram because I work for Honeywell. The base gasket was split. No more Frams.

 

I think those may be 1 heat range too hot. Which engine do you have and do you have any mods?

 

my 2002 4.6 had 115k on the factory plugs, my dad got to 98k with his 2003 5.4 fx4 and his were burnt about as much as they could be

 

97 4.6L 2wd bone stock

 

The correct plug for that engine is a SP-413, which replaces a AGSF32. You had the right plugs.