Hello all, I am in need of a little assistance in the wonderful sunny baghdad, Iraq.

I have a tymco sweeper which is an internation chasis. However, it uses a 6.0 turbo diesel such as what is found in the F250/F350 etc.. Basically I have a mutt of a vehicle giving me issues.
Its a little hard to start when cold. Once it fires up it runs rough. When I bring the RPM's up to about 900-1200 it shakes pretty bad.

I have:
Changed fuel filter
Checked oil level
Checked for oil leaks
Drained the oil and replaced with fresh 15/40 (which we use in all of our diesels)
I ran a power distrabution test. I found that when I cut off power to cylinder #4 I do not lose much power. So I replaced the #4 injector. It fixed that problem but not the idle.
After searching around I unplugged the ICP and same issue.
Recently the vehicle got a new FICM and ECU.

Any idea's or help would be greatly appreciated. I'm running out of options and getting desperate. I'm probably going to drain the fuel tank and clean it out to be sure I have fresh fuel. That is how desperate I am getting. I'm probably going to call international today and see if they can point me in the right direction. However, due to time difference wont be able to until much later today.