robfitz

I've had my standard zilla for almost a year now and have been pleased with it. I have had it set to the 60hp setting pretty much the whole time. The first time I romped on it it threw some codes. Qaud recommended changing fuel and air filters (which I did since I was so close to the maint time anyway) and I re-seated and added dialectric grease to all the connections. I've had no problems with it since. UNTIL!
About a week before a 750mile trip towing about a 5000# trailer I moved the setting to 100hp to try it out. The power gain was noticeable and I could hear the valve clatter more, which I assume is normal. I left it there.
Well, while returning home, just as I was cresting a mild hill - you know, when the truck starts to work less but before it's really in cruise mode - I noticed a vibration like a tire was out of balance. If I let off the pedal or gave it more go-juice the vibration would go away immediately. Because I was on a long trip with plenty of mild hills I had lots of time to diagnose.
Once I got to the point where I could make the vibration come and go at will I started moving the settings of the zilla. What I found kind of concerned me. While the vibration was happening if I slowly moved the zilla through its settings from 100 to off and back again the vibration (and valve clatter) would decrease/increase with each hp decrease/increase and completely vanished when it was off. I tryed this several times with the same results, even having my son pay attention to see if he could notice the same thing (just to make sure I wasn't nuts), he also could hear/feel the difference.
Assuming there was something wrong I turned the zilla off and have left if off.
The truck ran fine the rest of the way home.
Is this normal? Anyone ever experience this? I'm now a bit nervous about using the chip.