Changed the steering pump, now what?

[mhorning]

Well I wondered if anyone has every had their truck turn hard one way but not the other. My truck has suddenly started turning very hard to the left but it still turns easily to the right. The weird thing is that it does this only at idle. When I increase rpms it's as if the pump kicks in and I can turn the steering either way with ease. Let off on the gas though, and it gets difficult again. So I changed the pump thinking that would be it. But it didn't cure it. The only think left that I can think of is the steering gear. Anyone ever had this happen. Oh by the way, the truck is a 99 Silverado (New Body Style) 4wd. Any input would be appreciated.

Oh and I was reading what you guys said earlier about sensors. Is is possible my truck doesn't have one? The GM manual says that my truck should have Variable Assist Steering Actuator on the back of the pump. I didn't have one on mine. Just a plain old style pump, no electric to it.

Mike