Probably to much desired airflow at idle when in gear. This is especially a problem when cammed.

 

so I lowered the Desired Airflow table by 3% and lowered the values in the 1000-1600 rpm tables in the throttle cracker. Seemed to work. Thanks for the advice.

 

I started having a similar issue. I couldn't find Desired Airflow table on my HP Tuners.

Engine>Airflow>General Airflow.

Can you list how to get to the table?

 

On your 08 it's called Final Airflow Min. I believe. On your 03 I believe it's called Running airflow? Cant remember.

 

I use efi Live. Not sure how hpt list it

 

This issue seems to be a torque converter issue. When the tow haul button is pushed in the converter stays unlocked. I pressed it in while it was bucking and it stopped. kinda likes its locking/unlocking constantly

 

I think this could be the cause because my truck was perfect after the tune but later started to do that at certain speeds only.

 

Mine does this when in gear, but it's a T56. However, the idea may be the same. My tires are basically directly connected to my crank shaft when in gear. Yours are too when your converter is locked. Therefore, it sounds like it may be a converter issue like you may have discovered with the tow/haul button.

Mine didn't buck before the cam, and does every now and then after the cam. It's on decel like you said. Mine does it around 1200-1600 rpms. I believe it can be mended with some tuning.