Need some help trying to diagnose this. I have a 2005 GX470 with 148,000 miles on it. It has progressively developed a heavy steering issue over the past year. The steering at any speed seems heavier than expected it still moves fluid and is not choppy. There is no loud PS pump whine only slight noise when you turn it all the way to the left or right. There are no PS leaks any where and the fluid level is normal. I flushed the fluid and the changed the resivoir with its in built filter with no noticeable improvement. I don't want to just start throwing parts at this does anyone have any suggestions on how I should proceed? Any help would be greatly appreciated.