We are having an intermittent power steering problem with our 2009 Peugeot 807 and we can't find the fault. The steering becomes very stiff with the first drive in the morning but only when the speed goes above 20-30mph. You have to oversteer the car when cornering to overcome the resistance. After doing this a few times the power steering seems to correct itself and is usually ok for the rest of the day but the problem returns the following morning. We have replaced both the steering rack and pump with a reconditioned rack and pump but it didn't solve the problem. We have checked out all mechanical joints and everything is fine. The car doesn't show any faults when put under diagnostic testing. The problem seems to be worse on cold mornings. I would really appreciate any help or suggestions with this problem.