I'm not a mechanic but I can tell you that diesel and gas rigs are different. Take your diesel rig to a mechanic that works with gas rigs and he'll get lost. I've talked with a few guys that know quite a bit about gas rigs and I had to educate them and I just started learning about my diesel truck about 4 or 5 months ago when I bought it.

I tell you what, once you go diesel you'll never go back. On a gas rig, when you let the clutch out you have to give it fuel in order to keep it from stalling. The only time I've stalled my rig was when I was pulling a 12K trailer up hill from a dead stop or when I tried to run over 2 feet of iced snow in second gear while thinking I was in granny Low.
When I pull out of my driveway I don't touch the accelerator until I'm ready to start speeding up. I have also accidentally left the E-Brake on and my truck in gear and after starting it I dropped the clutch (I was in a hurry) and the truck didn't die but instead started lurching because there is enough torque to still move the truck with the E-brake set.

I'm sorry to say but your mechanic has mis-informed you. If you pop the hood on one of these trucks and look at the passenger side valve cover you will see it says, "International" which is one of the most respected big rigs on the road.

These trucks are freaking awesome!

Also, the advantage of the early 2000 rigs is that their fuel injection system is computer controlled but they have far less electronics and things to go wrong then the newer rigs (I'm the kind of person that sees a place for computers but still likes to keep things that I rely on, for the most part simple). This means that you, the owner can still work on it without having a computer tech background. To a mechanic this means trouble. For a diesel truck this means safety.
Older diesel trucks were known to run away when the accelerator malfunctioned. The run away was due to the fact that the fuel wasn't being restricted to the motor and since diesel trucks do not use spark plugs to ignite the fuel but instead compression, they would just keep going faster and faster tell either they hit something or threw a rod. You couldn't shut these motors off because they would draw the diesel from the fuel line as they were mechanical fuel pumps and had mechanical injection.

On the computerized injection, when you cut the electricity to the PCM and IDM or just the IDM these things shut down because the injectors are controlled by the IDM with commands coming from the PCM (IDM=Injector "something" Module, PCM=Powertrain (or is it just power) Control Module)

But the electronic system on these rigs are still very simple in comparison to a gas rig. They are much easier to troubleshoot in most situations.
The sensors on these rigs are mostly for vehicle statistics with the exception of the CPS (Cam Positioning sensor) which tells the motor the position at which the pistons are at so that the injectors can inject fuel at the correct time, the fuel pressure sensor and a handful of other sensors.

I personally find these engines easier to work on then any gas rig I've ever owned.

Also, if I've made any mistakes, someone please correct me as I'm still learning but I'm pretty sure I got everything pretty accurate.