95 Ford f350 7.3l perestroika keeps dying in very cold weather. Engine block heater plugged in at night. Starts right up no problem. Let it warm up 40 minutes drives fine for 15 miles then slowly decelerates until it dies and won't start again. 1st time in shop said bad gas and water in fuel. Replaced fuel filter, fuel heater, added fuel cleaner to stop gelling and water in fuel. Ran fine for two days gets below zero again and same symptoms. 3rd time at shop they drop the tank drain it said tons of water and broken parts in hose in tank clogging up line so no gas could get to engine. Again ran fine for 4 days this time and gets below zero again and same symptoms. Starts right up no problem then suddenly dies 15 miles down the road. Any ideas on what can be wrong?