In lieu of calling people names, I was thinking of ways to actually solve this problem (cheap). The most likely issue is that one of the PS hard lines got pinched during the 1st remove and replace of the rack. The quick rack isn't getting enough flow so it shudders. Once the engine RPM come up, the PS pump generates enough flow/pressure and the shudder goes away.
You apparently don't want to blindly start replacing lines cause they are expensive, you have to pay labor and its a messy job.
Why not go the other way. Find a machine shop and have them make you a slightly smaller PS pump pully (like 5% - 10% smaller). That ought to cost you less than $200 and fix your problem. Plus the nice part is that the install doesn't even require crawling under the car.... As an added benefit, you end up with a cool looking custom PS pump pully.