I have a '99 F550 w/a International 7.3L turbo diesel enjine. In the morning when I attempt to start the vehicle the engine turns over and over but will not fire (yes, I do preheat the engine first). I have discovered that if I plug in the block heater for one-half hour first then it will start, though grudgingly. Even after it starts it flutters and runs very rough until it warms up. Then, throughout the day I have no troubles and it fires up on command, each and every time. It also seems to have good performance after the engine has warmed up. The milage reading on the truck is 249570km. Any suggestions or solutions out there??????