2015 JGC Intermittent Smoking

My 2015 was fully deleted/tuned at 100k miles. I am currently at 141k. Over the past 10k miles it has started smoking intermittently. I am not talking about normal foot to the floor smoke... Sometimes when accelerating it will suddenly smoke for a few seconds, then stop. At times when driving 30-40 MPH and letting OFF the pedal, it will smoke; adding throttle will instantly stop the smoke. I recently did an oil change at 7k; at 5k I had to add 6oz of oil. This entire 7k miles was towing our 3,500 lb camper on an extended trip.

I have had two local mechanics look at it without any real answers. One told me I may have an injector going bad and at times it was letting excess fuel into the combustion chamber...but he had no way to check any of this.

It may go for miles/days without any of this happening; cold or hot, doesn't matter. Then all of a sudden it is boiling out blueish/black smoke. Pressing the throttle instantly stops it. Letting back off the throttle the smoke may or may not return. I have not been able to do anything to replicate these events. So, I am at a loss. Any tests, suggestions or guidance would be appreciated. Thanks!