Truck bucking

Have a 06 4.0 6speed. 130000 miles the truck just started to buck while driving doesn't happen all tHe time any ideas what it might be. I'm thinking a 02 sensor or some sort of sensor. I could be wrong.

 

When was the last tune up? Any CEL codes?

 

Last tune up was at 100000. Has 130000 runs great just once in a whiles at a steady speed it bucks but not at idle and I thought water in tank I put can of beet to dissipate water and this is my second full tank and still bucks once in a while. I have no check engine light on. Thinking gonna go and have my buddy hook up a computer to it and see if there is any codes.

 

Doesnt the 4.0 call for plugs every 30k?

 

Maybe I'll change them again. And may have a cracked coil too. Thanks