I'm having werid issues with power steering in my 2000 F150 4x4. When I'm in park, turning the steering wheel is no problem, but when I drive it turns very hard. Every now and then I'll come to a stop and turn the wheel slightly as im stopping and it kills my engine. No check engine light is on. Checked the fluid level and it seems fine, l also greased all the points that can be greased with a grease gun. Any suggestions on what this might be would be greatly appreciated. Thanks.

 

The power steering pump has to assist the steering box.
If either the pump is worn or the box has developed an issue that loads the motor.
If the pump is hard rotating, it loads the motor though the belt.
You have to understand as the engine rpm increases the pump pressure will normally rise. This makes the steering harder with a fault present.
To address this, the belt wear has to be included in the evaluation of the pump and box health.
The parts are 16 years old.
Good luck.