help with 1997 Ram Diesel 12V

Hey guys..new to this forum thing so if I mess up please tell me. Ok..here's what I'm dealing with..I have a 1997 dually with no mods..except that I lost the cat and muffler..it has around 60,000 miles on it. I changed the fuel filter and since then it has lost power...first it just would'nt pull, then it started missing and then would quit...like the fuel had been cut off..I can wait a couple of minutes and then with pumping the throttle and holding it down it will start like a flooded engine..sputtering and missing..with a big cloud of black smoke, then will finally pick up and go on till it gets in a pull or until I really tach it out then it does it all over again..idle is fine..it will sit and idle all day..the wierd part is that when it is missing and dying out it blows blue smoke..how can it be lean and rich at almost the same time?? I have put a new lift pump and also a new overflow valve on it..three different fuel filters..bled the dickens out of it..now I have no idea of what to try next..any suggestions would be greatly appreciated..thanks!

Are there any fueling enhancements done to this truck? I could be wrong, but it sounds to me like it runs fine until a real load is applied against it and it overfuels. This causes the egt to rise too high and the computer defuels it to save it. Don't worry too much about blue smoke at startup that's just burnin a little oil mine does it a little too. You shouldn't need to a use any throttle to start it either. The truck probably had a large torque plate in it and it doesn't have the airflow to match. Like I said I'm not sure but it is a suggestion.