Transmission shuddering 2014 6 spd transmission shuddering at 35-50 mph

[Kkdj6369]

Just got the 2014 Silverado 5.3l 4x4 back from the dealership from having the entire top end of the engine replaced ($9000+) at 106,000 miles. Noticed oil on the plugs & immediately started smoking. But NOW - 5 days later, the truck shudders at 35-50 mph, especially if going uphill at a low speed. Does anyone have any suggestions for what this is due to or how to correct it - preferably without spending another $5-10k. 

This was a great truck up to 100k miles, but now it seems to be falling apart.  Put a Hypertech programmer on it in late 2017/early 2018 to turn off the afv, (at about 70k miles & that's all I used it for), hoping to avoid the problems that causes, but no luck. Now this transmission thing is happening.  It used to shift hard at low speed & when cold, but this shuddering is new. 

[Kkdj6369]

And six days later....

This truck acts like the transmission is going to fall out. 

Error codes 0700 & 0796.

Oddly enough, when 4wd is switched from off to auto select, it doesn't do anything crazy.  

[Snowcamo]

You know you could of gotten your trans and engine rebuilt with upgrades by a shop if you searched hard enough.