advice on 1997 dodge ram

Idles rough,dies out after running 20 mins,starts good next day,problem starts again after 20 mins run through water dies out starts right back up SOME 4X4

Need Help Dodge Ram 4x4

how many miles are on the truck? when was the last tune up? you could have a plugged or at least dirty fuel filter (those are fun to change, you have to either drop the tank or lift off the bed to get to it)
also, how's you distributor cap and plug wires? you might be getting moisture in the ignition system someplace.(my guess would be either a cracked distributor or a cracked or loose wire either on the coil or distributor)
hope this helps ya out some,
Keith

It's not a boat.