i have a stage 1 mpi on my 2008 nytro and it ran good for two years. had to put a new injector and starter in it this summer because it stared blubbering latst year on and off, now it does it all the time cant get it to stop. The shop checked all the pumps, filters, injectors. I have no clue whats going on it backfires wont go full throttle or anything. Any one have any ideas or probs. like that?