lestat964

My 2000 Nissian Frontier Crew Cab V6 2WD AUTO, is at the nissan dealership right now. During evening drives 5-7pm or so i hit the freeway for about 20miles, then I get off and go up and road that had a nice size incline. about 30 yards into the incline the gauges go out on the dash. gas gage freezes were its at, evn though im burning gas, speedomiter goes to 0, rpm's go to zero, but the dash is still lit. the last few times when this happens the truck started to serge when i felt like i was going about 15 - 20 mph. Nissian cant get it to do it for them but there not taking it up any hills or trying it at night, there stumped. When it happens is I stop the truck and turn it off for about 5 min, turn it back on, it all works fine, and dosnt happen again for the rest of the drive. Any know what could be wrong? thankyou in advance for any help you can give.