Welcome. As far as your question.. some are reporting a decrease in MPG.. and honestly, if you're not happy with the truck I would look into trading it in. You can tune it to get some of that back, but then your warranty is likely gone if/when you need it.
Welcome! You're not alone as most have had the same issues. I'd recommend reading the Settle Forum for more information around the recall/settlement for EcoDiesel owners.
https://www.ecodieselram.com/forum/forums/ecodiesel-settlement-information.36/
Welcome! That's a very likely scenario based on the previous posts we've had here. Have a look in the engine talk section as we've got a few threads here on this issue.
We've got a million threads on this topic here with a few names of people that might have what you're looking for.
Try searching "tuning".
https://www.ecodieselram.com/forum/search/84038/?q=tuning&o=date
Welcome, a few topics around additives here.. and really most just use what they think is good for the truck. I've used a few, but I'm not sure if it helped or not over the years...