The truck is not mine, but i'd ask for advice. The truck is a 03 v6 silverado a4 rwd. the issue is it will drive perfect for about 20-30mins, then completely lose all gears(feels like its in neutral more so than slipping.) shut the car off for 2-3mins and then it is perfectly fine again for another 20ish mins. My guess is eletronics, has it is totally fine after shutting it off for a while. does anyone know the continuity check steps for the chevy solenoids and/or control unit/module? someone have said transmission unit, solenoids, and someone has said trans filter or pump. But it seems to be a straight forward system as it is better after a few again so i find it hard to believe it's mechanical failure. truck is completely stock and no codes showing.