please help with power steering!!

[SnS C10]

hey guys i havnt been on here in awhile. last time i posted it was about me taking a road trip to ky from california. well i made the 2200 mile trip without one hiccup from the truck at all. 2200 trouble free miles. well, when i got to ky, i noticed that sometimes while steering, the wheel would stick a little and not turn freely. i changed the fluid and all and it did not help. so i figured it was an old pump so i got a new one about a month ago and installed it. i did the correct procedure for bleeding and all, replaced the hoses too. it worked great. but....the wheel is still sticking sometimes, though not as bad as the old pump. also about 3 weeks ago there has been a rattling/light knocking noise coming from the engine. so, to check that, i unhooked the altenator/ water pump and the power steering pump. so the only thing turning is the crank....start the engine, noise is gone. next, i hook up the steering pump. now only the steering pump and crank are turning, the noise is back. with just the altenator and water pump hooked up, the noise is gone again. what is going on with my steering pump? why would the wheel be sticking and why is there a rattling/knocking noise coming from the pump itself? oh yea, just incase you guys ask, the pulley is on tight. the fluid has been a little high since i put the new pump on though. can too much fluid ruin the power steering pump? tell me what you guys think is wrong. thanks a lot and thanks for everyone giving me advice for my cross country trip, it helped a lot