Curious if your plug fouling has been Wet or Dry fouled?
This may be of help on the plug readings.
https://www.youtube.com/watch?v=lVCs5gWLUyI&t=169s
If its a Wet fouled issue a compression check will help you see if its a Motor issue Top end vs Bottom end.
If you have a Dyno shop nearby? a quick tailpipe AFR check my reveal any possible mixture issues.
Lastly Roush has somewhat of an reputation for
oil consumption. Not saying they suck, but they advise higher
oil consumption is normal in their motors. Info-->
Roush Engine Warranty Exclusions.