Wtf could it be????? Vibrations when letting off the throttle at 60kmh+

2017 taco.
Old man emu kit
Upgraded wheels &tires.
I have had trouble getting balanced properly for along time.
Finally got the needle bearing done. Fixed a lot of vibration issue.
I have now developed a new issue. If I am doing between 60-90kmh and let off the throttle, I get vibrations through the entire truck. To the point where the passenger felt unsafe. I believe my lift is 2.75" so no need for changing driveshaft angles???
Any thoughts before I take it in someplace?

 

This could be a driveline angle issue. You might have to get under it and see what you angles are. Do you have a carrier bearing drop installed?

 

Check the carrier bearing.

 

No ...i do not..
Please enlighten me....
Have I done further damage or all good?

 

May just need shims. 1 degree for each inch of lift to get the angle happy again.
The carrier bearing spacer is just that a small plate that lowers the carrier bearing, changing the drive shaft and pinion angle on the third member (differential)

 

Dropping the carrier is simply installing spacers between the mount and the bearing housing. By dropping it down you can improve pinion to driveshaft angle. It can be a premade kit like the link below or simply some washers and longer bolts. I would also suggest checking the condition of the carrier bearing to make sure it isn't damaged and causing the vibration.

https://www.bilsteinlifts.com/shop/...MIpeyJ2Orb5wIVsRx9Ch2jjQgvEAQYASABEgL-W_D_BwE

 

You want to keep this as straight as possible.