Low Speed bounce

Here's what's going on & you'll give me your opinion. After I lowered my Dually, I now get a bounce at low speeds. From 35mph down (my speedometer needs calibrated so I'm guessing here) I get this bounce until I start speeding up. I got the tires computer balanced so I don't think it's them.
I took the overload springs off to lower it that were on top & the bottom spring out of the pack. I installed new DJM lowering shocks as well.
Any help herer? Is this normal?

Does this occur all the time or just until the tires have warmed up? Most tires will develop small flat spots after sitting for any period of time and these will disappear after the tire warms up.

I'll be honest with you I drive it so little, I don't drive it enough to know.
I'll try & remember to pay attention to it the next time I drive it & respond. Sounds like old bias ply tires.