Stiff Steering

[Valiant]

Ok. Here is a head scratcher for you. I have a 2004 2500 ram with a 5.7. If I drop from Drive to 2nd gear below 40 mph my steering is fine. If I accelerate above 43mph while in 2nd gear, the steering gets very stiff. The faster you go the stiffer it gets. All is normal while in Drive at any speed. I did recently replace the steering pump with a new after market brand.
Any help is appreciated. Thanks in advance.

 

[Dodge 1500 4X4]

What condition is the drive belt and idler pulley in, sounds like belt is slipping.