Huge amount of gray smoke from a Cummins Diesel?

This is on 1998 2500 4X4 Dodge Ram Truck with a 24 valve 5.9 Liter Cummins Diesel engine. The injector and lifter pump was replaced recently but still had a problem starting. Then two weeks later he adds Fuel System Cleaner, Fuel Injector Cleaner, and Oil Detergent into the truck. After a couple of days the truck goes from a light amout of smoke into blinding amounts of grays smoke. No one seems to really know where to start with this truck so far. Guesses made at Automotive Shops so far are Fuel Injectors to much fuel. Another one said his best guess would be a burnt valve. Personaly I don't know diesels really my wild guess is could this thing be going through a timing problem?