Hi and welcome to mightyram. This is a tricky one. It could be due to the fact you've taken everything apart that something has been altered that isn't obvious. Was the steering box complete with the pitman arm or did you use all of the manual link assembly? The power steering shafts might be out of alignment by a spline if you've re-used the manual box pitman arm (?). What are all of your front end components like as far as serviceability? I think the belts should be fine as it will only affect power transmission through the hydraulics if it's slipping and if the steering box had issues, you'd hear and feel it under normal conditions. Get it in for an alignment and see what the shop has to say.