1997 Dodge Caravan won't start

This is a strange problem. Occasionally, When I start this van I get no fuel gauge reading, no shift indcator, no odometer reading and no temp gauge reading. The engine will start but only run for 2-3 seconds and die. This may happen for a short time or may last 2 or 3 days but will always start sfter waiting awhile. I have cleaned battery cabbles, put on new ends, cleaned all the grounds I can find. I have replaced battery just becuase. Took lower dash apart looking for bad connections but I can't find any. I got desperate and took it to a dodge dealer and they found the same thing it starts after a couple of days. But when it won't start it always has the same simptoms, no dash and runs for 2-3 seconds. I'm stumped