My truck surges also, but it does it at about 50MPH and over when the throttle is only slightly pressed (down hill in cruise control). I usually just drive a liitle faster or coast when I get to the grades.

 

Agreed. Had the exact same issue with my truck (2nd gear, 15mph, surging), and had lived with it for the past year. A few weeks ago, I replaced the solenoid with the one called out in the TSB, and I cannot duplicate the surge (it was pretty predictable before).

Hopefully this helps.