Pulled out the autolites (5224 for the 3.7L) and measured every plug. On average, I found a .010" increase in gap from .035" initial gap. 4 of the plugs had electrodes that looked like the were taken to a bench grinder. Also, I have lost about 3 miles to the gallon in the last month (20 mpg to 17mpg).

The Fix:

Decided to try something a little different. Bosch +4s. Now, I know a lot of you guys didn't like them. However, I don't recall seeing any negative feedback for the 3.7L. So, based on previous experience, we will try these to see if they do anything for the milage. I can tell you that I do feel a little more power with the Bosch's, but then again that is based off of autolites that were trashed with excessive gap.

I will post pics of the plugs tonight.

 

i changed mine out at 75,500. gaps were from .065-.070

looked like a burnt out fire cracker

 

although the Bosch+4 plugs have not worked well in the 3.9/5.2/5.9 magnums,
there have been several good reviews when the Bosch +4s are used in 4.7 V8s

if you like to experiment
consider cutting off the one of the 4 ground electrodes
that block the growth of the flame toward the center of the combustion chamber
kinda make them into custom indexed Bosch+3s
so to speak

in my opinion
the Bosch+4 design has two main features:
... it has a large 0.060 inch gap
... with 4 ground electrodes one of them ends up close to the hot exhaust valve where the spark-over voltage will be lower for hotter metal

the combination of these two features makes for slightly faster combustion that is equivalent to a slight increase in ignition advance

the stock pickup version of the 4.7v8 ignition is retarded about 12 degrees at WOT so that it can run on 87 octane gasoline, judging from the Jeep 4.7's that were tuned for premium gasoline.

 

my stock champions were bad. the electrodes were almost gone. now running the nitrous i tend to change my plugs more often so they dont look bad. running the 3923 plug

 

Mine were worn out!