Vibration under load

[vibratingchevy]

Hi all,

   2017 Silverado 6in lift with 35's. I have a vibration only at rpms 1250 to 1800 under high load. Cruising on the highway at 70 and going uphill the truck feels like it has a misfire. Stuff I've done already...

Changed torque converter, changed axle bearings, changed plugs and wires. I've backed off the e brake shoes. Turned of fuel management. I have a diablosport tuner and can watch the sensor inputs. Any time the engine load is above 90% it will vibrate. Dealer blames the tires (of course). It's driving me nuts. No other drive ability issues. I've heard of some having issues with the driveshaft, but this started like 5000 mi ago. Any ideas?

[CamGTP]

Driveshaft angles and u-joints always come to mind with lift kits.

[MikeBMW]

Also, it's important to have the tires road force balanced to detect tires which might be slightly out of round.

[vibratingchevy]

Thanks for the reply. Wheel balance in my experience is a function of speed. Speed has no effect I can get it to go away be downshifting and going faster and there is no vibration in the steering wheel even after tire rotation. 

This is 100% tied to engine load. I can be traveling at 70 and no vibration engine load at 60% and start on a hill keeping the same speed, the engine load goes over 90% and it feels like I have a misfire. Exactly like a misfire but no codes, and no misfires detected on a scan tool. It's driving me nuts!

[vibratingchevy]

I wanted to give an update. Took it to a dealership and they tested everything and said everything checked normal. The did find an update for the TCM. They updated it and like 95% of the shudder is gone. You would think I would have got notified of an update like this. I am now out 2k because no one knew there was an update. This is the second dealership I've had it to. Truck has less than 100k. Amazing