Originally Posted by cheese_man
autozone sold you resistor-less spark plugs
( the coil completely discharges before it has time to spool another charge )
the resistor type plugs prevent the coil from completely dis-charging , therefore it has enough time to spool another charge .
you will be better off with just the basic champion spark plugs
i am presently using the new CHAMPION COPPER PLUS plugs
and they work damn good
AGSF22P vs AGSF32FM
A = 14mm thread, 3/8 gasket seat
G = 3/4" reach
S = Suppressor (Carbon)
F = Tapered Seat
First number = Heat range
Second number = Cannot remember
P = Single platinum-nickel electrode
FM = Finewire platinum-nickel centerwire electrode, nickel plated shell
PM = Single platinum-nickel electrode, nickle plated shell
Factory 3.0 plugs are AGSF32PM / SP-493, one step colder Motorcraft plugs are AGSF22FM / SP-500.
Given what you pulled out was one step colder than factory, someone may have been trying to take care of a pinging problem. "Runs like crap" doesn't really describe the problem too well, does it ping/knock? If so, the counter professional did not sell you the wrong plug, but they may not be aware of the pinging problem of most 3.0s.