Do you have the stock shocks still?? if so get rid of them and get new shocks. Bilstiens perhaps.
I am running something more like a 33", they are 275/70/18s. I think I just need new shocks....If your running 35" tires at 35 psi that may be part of the prob as well. What load range are your tires? If the are load rand D or E then you need way more air in your tires. I have 325-60-18 on my truck, load range D and I run about 50psi. It helps alot with it pulling and gets rid of the mushy handling. Going by what's on the door sticker is for a stock application. Does not apply to oversized tires. This is coming from someone that has had 5 lifted trucks over the years. I would also swap the shocks to bilstein hd as well. They make a world of difference. If you want a really good smooth ride then you will need to go with a Coil over set up like radflo.
This might be your problem. Just about every 275/70/18 tire that I've seen, except one (the BFG Rugged Trail T/A), is an E rated LT tire. These tires are built heavier to carry loads at higher pressures and it results in a stiffer ride. Your shocks are probably no good either if they are stock, but the LT tires will definitely stiffen the ride.I am running something more like a 33", they are 275/70/18s. I think I just need new shocks....