Truck lugs

[Kodiak450]

On ocassion when the front end dips down on and incline and you are oing from drive to reverse the truck will lug dow for a moment almost acting like it was a manual tranny and you were starting in the wrong gear. The stock t-converter was replaced about 30K miles ago. I checked the fluid level and color both look good. The mystery is it doesnot always do this, I was thinking maybe the filter and fluid need to be changed, anny ideas.

Thanks

 

[Crusin350]

What truck do you have? Year, model, engine and all that good stuff will be helpful for others who may have an answer.