Today was the 1st day driving my 97 ram 1500 5.9,auto,4x4 to work.On the way home i set cruise at 60.I noticed that when I pulled a grade the air coming out of the vents switched from the dash vents to the defrost vents and back again every time it pulled a grade.Im guessing a vacuum leak somewhere.I have not checked anything yet,and I dont know if plenum was fixed yet either.I figured id ask here first,since i found all the information I needed to do front axle seals and u-joints on the forum.

 

https://dodgeforum.com/forum/2nd-gen...ild-vents.html