Is the vehicle maintaining the same speed, or does it speed up and slow down? Are you running larger than factory tires on stock gears?
My first thought: I don't think this is a cruise issue, I think it is your tranny coming in and out of full lock (torque converter). This will be exagerated with large tires and stock gears, on hills, or driving into the wind. By the way, my ZJ did this for 3 years and 35k. I was running 32's with 3.73's. It really only happenend with a slight load at high speed (hill or towing). The Jeep was just working a little hard and didn't know if it could lock up in overdrive, or just stay in high gear.
My first thought: I don't think this is a cruise issue, I think it is your tranny coming in and out of full lock (torque converter). This will be exagerated with large tires and stock gears, on hills, or driving into the wind. By the way, my ZJ did this for 3 years and 35k. I was running 32's with 3.73's. It really only happenend with a slight load at high speed (hill or towing). The Jeep was just working a little hard and didn't know if it could lock up in overdrive, or just stay in high gear.