My power steering on my '86 f150 5.0 is weird. in the morning when it is cold, the steering is quite heavy and doesn't want to return to center. Once the car warms up or the sun comes out and warms up the car, the steering works fine. Only happens in the morning cold. There was a VERY small leak that was confirmed with dye, but that was fixed and the problem persists. Please help, any ideas are appreciated.

Thanks all.