Sorry for the delay in replying. My Verizon e-mail service is down for maintenance going on two days now. I am not receiving automated messages that you posted another comment. Hopefully that will be fixed soon.
The rack and pinion can cause the symptoms you described, especially if it occurs when the engine speed is above idle. This happened to my mother's Grand Caravan, but it is not a common failure. I would not suspect the steering linkage unless it was binding all the time.
The Chrysler dealer has an inline pressure gauge to measure power steering pump pressure, but when I worked for one as their suspension and alignment specialist, I only used it about once every few years. All it does is measure the maximum pressure the pump is capable of producing. If you ever find that you have good power assist at idle, the pump is working. The wear of the vanes in the pump, which is somewhat common, will not cause an intermittent problem. It will have low assist all the time at idle.
Sunday, March 28th, 2010 AT 8:14 PM