89 454 tbi running like crap

[1track]

alright, just bought this thing last week and it runs like crap. It will miss, cough, stutter when accelerating, acts like it is running rich. It is through codes 33 and 44, the map and O2 sensors have been replaced, still throughing codes intermittent while driving. Now it is very hard to start. It will crank and crank but not fire, takes forever to get started when warm. If it is cold like first in the morning it fires right up. I haven't replaced egr due to cost and the coolant temp sensor seems to be reading okay, after running awhile I got around 1500 and figured about 100+ degrees. What now? Thinking of just junking the bbc and swaping in a cummins