2013 RAM 1500 5.7 stumbles

[pamante]

2013 RAM Sport 1500 5.7 with 103k on it. Completely stock. Set the cruise control at 75 and when I hit a slight incline it stumbles, like it wants to downshift but doesn't. If I stomp on it - it goes! Just ordered a set of plugs - can't hurt - no CEL codes

Nothing in the display to indicate a problem.
Recent Cooper ATs dropped gas mileage 1.5 MPGs but the problem exists before the tire change - has become worse since then but I'm driving alot more

Trans fluid pink and full
Use Mobil 1 and K&N oil filters - just changed - nothing obvious in the drained oil or on the dip stick
150 highway miles everyday with cruise control set at 75

I'm hoping to get 200k out of this without any major engine work - got 180k out of my 2001
ANY help would be appreciated

 

[Fast69Mopar]

2013 RAM Sport 1500 5.7 with 103k on it. Completely stock. Set the cruise control at 75 and when I hit a slight incline it stumbles, like it wants to downshift but doesn't. If I stomp on it - it goes! Just ordered a set of plugs - can't hurt - no CEL codes

Nothing in the display to indicate a problem.
Recent Cooper ATs dropped gas mileage 1.5 MPGs but the problem exists before the tire change - has become worse since then but I'm driving alot more

Trans fluid pink and full
Use Mobil 1 and K&N oil filters - just changed - nothing obvious in the drained oil or on the dip stick
150 highway miles everyday with cruise control set at 75

I'm hoping to get 200k out of this without any major engine work - got 180k out of my 2001
ANY help would be appreciated

Would this be your first set of spark plugs at 103K? If so, it's time. They are 8+ years old with so, so many heat cycles. Porcelain over time breaks down and allows the ignition energy to escape through the base of the plug where the porcelain meets the metal.

If you pull a spark plug out and see a rusty looking burn ring around the base then they are breaking down fire. This will easily cause a misfire under load.

 

[Desertdawg]

My '13 Laramie broke a valve spring @ 98k. It barely ran to a local dealer, and since I had extended warranty coverage, I put in a reman long block.

 

[MADDOG]

Clean the throttle body. Over time they get pretty dirty and that can affect throttle response.

 

[Treburkulosis]

Have you done any maintenance to it? I guess thats where we need to start. It could be lots of things.