I have a similar noise and feeling in my 99 Rodeo. At first it only occurred when it was near freezing during turns where I encountered bumps, potholes and pavement irregularities. I could feel and hear it underneath my feet.

What I discovered (after sometime) was that my front shocks slip back and forth on the bolt and polyurethane pieces that connects them to the shock mounts causing a knocking noise and vibration. This is largely due to my custom fitting of the Rancho shocks to my Rodeo. I haven't done anything to correct it and I've been driving like that for ~6 years.

Good luck with yours.