Spongy feel going over humps

So first off let me say I'm not a mechanic, know nothing more than changing oil and brake pads, so don't rag of me haha. Anyways 2 weeks ago I bought a 2009 Tacoma double cab off road edition. 6 speed manual about 50,000 miles. Test drove it loved it felt the ride was fantastic so I made the leap. I live on an maintain a 27 acre apple orchard, so about a week ago I decided hell I'll take the new truck up the dirt lane into the orchard. It's a bit of a bumpy lane with humps and small swails for draining. As I drove over these humps the truck had a bit of a spongey feel to it with a bit of a clunk when hitting the humps. Almost as if the steering would be sucked towards the way the hump faced. Is this normal? I was not in four wheel drive. Could it be suspension related, steering what advice can you give. I have a warranty on the truck so I'd like to figure out what I should do before it runs out. Thanks in advance!!

 

Is it lifted? If so, probably needs an alignment. If it's not lifted now, it probably was before trade in, and probably needs a alignment.

Bump steer.

 

It is not lifted now, not sure if it was before I purchased it. Today when I started it the tire pressure light was on, not sure if it could have anything to do with it. It's not my daily driver so it occasionally sits for 4-5 days at a time.

 

One low tire can make things feel real strange....air them up to spec and go drive the same area again and see if it goes away....had that feel with my Tundra...turned out to be a low tire (nail) and it doesn't have the air sensors.