V-tek chip failure on Honda Element - or something else?

A couple of weeks ago, my wife was driving our 1-year-old Honda Element (manual shift) when it began bucking in the lower gears. The problem would become better when she upshifted. The dealer told us the problem was a defective v-chip, which regulates valves, and said the problem would be worse with higher RPM’s meaning it would be worse in lower gears. We got a new v-chip and all seemed well.



However, the bucking began again when I drove to the store. It was especially noticeable in 2nd and 3rd gears.



But when I drove it to the dealership for the second time, I left the AC off (it’s been unusually hot here lately), and the car didn’t buck once! So: is it the v-teck chip, or some other problem?