Just got a 2001 F-250 SuperCrew Powerstroke 4x4 with 85,000 highway miles. This is the family's first diesel. How many miles will this engine/drivetrain go? I doubt it ever will see any offroad or towing. Also, are there any trouble spots we should look out for or any basic modifications that will improve durability or performance? I've heard one should let it idle for 30 sec or so before killing it. Is that true?

 

The engine will probably outlast the truck. Should be good for 300,000 if well cared for. If you have an auto tranny, that will die much sooner if it hasn't already. Try Suncoaster transmissions when it DOES fail, and it will.

Most guys add a simple chip to the computer for better performance. It is simple to add and gets lots of power results. Trouble is though, it adds stress to your tranny, See above paragraph

Some of the 7.3's had "cackle" that you can hear while idleing. I think it had to do with fuel delivery issues. Others have experienced loose turbo bolts on earlier models.
Other than that, the 7.3 is a work horse.

You should allow your turbo to cool down before shut-off. Let it idle for 1 minute before turning off the key.

Keep up on basic maintenance, fuel filter, conditioner in the coolant, oil and filter changes, and it will be happy. Just watch that auto tranny