TruckCanuck

I have an intermittent problem where my 2000 year 2500 6.0l won't shift out of 1st gear on acceleration. Just before this happens the dashboard display lights flicker once or twice. 97% of the time the truck shifts great - no tranny problems. It seems it is an electrical issue but my local dealer is stumped. He has only put one hour into it though. Not sure I want to go digging at $140 per hour so I thought I could ask the forum for help....Thanks