I was having an issue with stiff steering on my 2007 w ~240k miles. Did a power steering fluid flush (ATF fluid) and it didnt help so next looked at the intermediate shaft. Lubing the u joint helped loosen the steering for a short period of time.

A local independent shop replaced the lower shaft and yoke (OEM parts) and it was a HUGE difference. It was almost too loose as I could now turn the wheel with only a single finger as it offered no resistance but I was ecstatic with the repair. Tech said he had trouble getting the steering wheel to line up straight after but by the time I picked it up it was fine.

Well now 2 months and approximately 2k miles later the steering has stiffened up again.

The PS reservoir is at the proper level and the fluid is new. Any thoughts on what I can check next?

I found a post that mentioned to pump some grease into the ball joints so I may try that next since its easy and cheap, just wanted to see if anyone had insight as to why the steering would be fine after replacing intermediate shaft and then stiffen up again in a short period of time.