I have had a 4d56 mitsu running without it's turbo (slowest thing ever!) but had nothing loke the simptoms described...what I am trying to say, leave the turbo alone, if you remove the turbo all together, the engine will still work and move the car to a somewhat good speed. it will take longer only...this is true for gasoline cars with a turbo also (had a Colt once)...the turbo is not your problem fuel delivery might very well be your issue...all are saying valid points, but thinking that the turbo is indeed the problem, as I said before, drive it without getting it to above 1800RPMs and see if it fails, turbo starts at such engine speed...again, I apologize if something is not written correctly, spanish is my native tongue...