So I just got my truck back from having all the lifters and pushrods replaced under warranty for a lifter failure, 70K miles on 6.2 engine. Now, I just noticed when I'm driving around in the city and I give it a little gas, it down shifts and the engine feels like it hesitates/shakes for a second then goes. Doesn't feel like the trans, feels more like motor hesitation. I do have a Black Bear tune that removes the V4 mode junk. I took it back to the shop that did the work and they said they can't make it happen and find nothing wrong. Not sure where to go from here. Only happens when it downshifts in slower speeds, i dont notice it at higher speeds on the highway.