I Need Help

God, I hope it is maybe a boost leak. The car started halting and missing after the heavy load from boost in second and third when I was slowing down. I checked connection for mas right after, and the i/c connections, but I am going to do it again. I just have bad feeling about the way everything has gone down here. HAS ANYONE RUN INTO PROBLEMS RUNNING C16. Does it cause problems to oxygen sensor, it has caused plugs to foul? I am not running anymore boost (20psi) then before. I had planned to re-tune and turn it up later. I am just pessimistic and lost. This has been a painful start for me so far this year and it looks like the end for me too. No way I can afford another engine until maybe winter. Too many problems and hours on the car.