Ag380 rough ride

I got a w900 with a 260 WB and ag380 suspension... I've changed shocks all around, Cab shock, cab airbags, front cab bushings, even all 4 torsion bars/torque arms, alignment, played with ride height and Cab leveling to get it to ride a bit better but I still get a hard bounce going over bumps and sometimes even a little wobble going down the highway in the rear. The truck was used with tankers previously because the fifth wheel is raise could this contribute to the ride?. Also was thinking of rebushing the "C" leafs springs (I did the tug test they seem to be ok though). I rode in a w900 with AG400 with the short bags and it rides like a dream compared to mines. It has 4 leafs for the front compared to my 3leafs and it has about a 280wb... But I've heard so many ppl telling me that they can't tell much difference between the 380 and the 400... Any suggestions????