Hydraulic Power Assist Steering System problems of the 2003 GMC Sierra

2003 GMC Sierra crewcab 4x4 long bed 8. 0lt. (1) I have a problem with the power steering system that when I am at idle, stopped or sitting with my foot off the breaks I can hardly turn the wheel. Only when I move the vehicle some can I then turn the wheel and still it can be difficult. (2) the dealer has replaced the hydroboost system in an effort to remedy the problem. I have brought it back to the dealer twice for the same problem and both times when I picked it up it still had the same problem sitting right there in the dealership. (3) this problem I believe is in the power steering pump not having sufficient flow to handle the friction the tires create at stopped or slow movement. Maybe a higher flow upgrade pump is in order here but the dealership told me not to bring it back anymore for this as there is a remedy coming out soon. I have been waiting for a year now with the problem getting worse and no recall being issued.