Anyone heard of all the guages dropping to zero like a power failure for a brief moment and when it does the transmission shifts extremely hard, or not into 3rd? Could this be a computer problem?

We had an old international dump truck that would do that. Every thing would drop to zero, then jump back up..... I think they told me it was something loose in the dash and the jerking would break it free and cause a reset. Never mattered though and still does it to this day. So, your not alone, but I don't know how to fix it.