pulse in power steering

I assume that by the term 'pulse' you mean that the there's a bump or jerk once for every rotation of the tires. The only thing I can think of is a lumpy tire, like tread separation, for instance. Check to see that the tires are in good shape without tread bulges or worn spots on the tread. I suppose there could be a faulty wheel bearing, check for that too. If you want to find a specialist, here's a directory link for you: https://repairpal.com/ford-repair-in-houlton-maine

May be the power steering pump itself...hopefully you had that checked before replacing the rack

Check the steering shaft u-joint under the hood. The joint is vertical and can hold moisture when parked. Oil the joint liberally from the top and rotate the steering wheel, should displace the moisture and allow it to turn smoothly, if not, joint will need replacement.