Isuzu Repair: rocking car at high speeds, shocks and struts, nissan pathfinder

Question
QUESTION: Aloha, I have a 97 Nissan pathfinder, but I figured this question could apply to any car. When at speeds over 40 my car will start rocking back and forth. It's not constant only at certain parts of the highway, if I just take my foot off the gas it stops. I replaced the shocks within the last couple of years. I took it to Nissan and they said the shocks and struts were fine and it passed the bounce test. I'm at a loss.

ANSWER: DOes this rocking include alot of vibration and roughness? If so your driveshaft and or rotors are warped and your driveshaft could be bent. The rocking could also be an alignment problem on your vehicle, have you thought about having a steering stabilizer installed?

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QUESTION: There is no vibration nor any roughness. I've also taken mu hands off the wheel and the alignment seems fine. What would cause a driveshaft to be bent? I have'nt had any accidents and the rocking only occurs along the parts of the highway that isn't as smooth. I do have high mileage 167,000.  Thank you for all your advice.

Answer
The only thing I can think of is a rock or object could strike your driveshaft, or the balancers could have fallen off, but I doubt that is the case. Did you get a second opinion on the shock and strut test? I would, Also you might have uneven tire pressure. I would recommend having  your leaf springs checked as well(if this vehicle comes with leaf springs) Your high mileage is quite impressive as well, that states you have done something right! ALso rolling and pitching is caused by a faulty steering gear, and worn or broken front alignment parts. I will do some research on your vehicle and let you know ok? we will get it figured out!