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I wasn't able to print for a while since I had to redo my hot end with a new thermistor, hoping to finish tomorrow, still have odd skew though, my idlers move fine, the belt is tight to minimize backlash, linear bearing upgrade done I am completely out of Ideas and I'm almost tempted to give up if I cant get rid of this skew soon.

What kind of skew are you experiencing? X/Y, X/Z, Y/Z? How are you measuring the skew?

It would be easier to diagnose if you could print a cube object, then provide the measurements and a picture that show the skew.

If it's an X/Y skew you could show it by taping a marker to the head and drawing a square on paper.

I posted some pics a while back , it was x/y skew but then I did a bearing upgrade and now it is just x

Hi Tom,

X axis is the most loaded one... so it is not surprise.
I had once a "huge" (several inches) skew on X axis that was causes by the pulley that was slipping on the stepper motor shaft.
When the motor is getting hot, the friction between the shaft and pulley was not enough to transfer the peak torque and at each layer I had a big shift in minus X direction.
I had to ream a bit the pulley's hole to fit it when I assembled my printer. Probably I removed a bit too much material which caused this issue.
I have fixed this by removing the pulley and mounting it again with a drop of Loctite.
To be safe I did the same for Y & Z axis pulley as well.

Now I have no slip, and overall a very good repeatability.

my toothed pulley is on the stepper good, It's not going anywhere It was pressed on with a vice it skips steps instead of slipping if you try to stop it