Thumping and ch-ch-chugging at 1200-1500 rpm

Hi Folks,
Please help me get some insight into this issue I have.
2016 d13 del'd I-drive
Between 1200 and 1500rpm, while accelerating, climbing or pulling a trailer, and more recently even just going down the road, I hear and feel a "thumping". Some describe it as a knocking or 'put put put'-ing. It is not very prominent when bobtailing, and not present while just idling and revving the vehicle. I just had an overhead done which did not improve the issue. Some drivers have experienced worn cams to be the issue, but my mechanic took a close look at the cam today and didn't detect any wear. He then said it might be a torque converter issue. Another mechanic said the automatic doesnt have the torque converter and that some cam wear is not detected by naked eye and will need the cam to be mic'd (sp?). Most recent service included an oil change as well as a replacing faulty sensor at the transfer case which caused involuntary engine shut downs. I'd like to upload a video of the sound but i dont know how

 

No, 3 separate mechanics. Overhead was done on the road in El Paso. Second mechanic in MD did additional diag and inspected cam and suspected torque converter issue. Third mechanic working on another truck of mine in TN mentioned over the phone no torque converter is present.
So far I'm no further than where I started

 

Mint