starts, then immediately stops.

Howdy Folks! I have a 96 Isuzu Rodeo with a 3.2L V6. I started out by having problems witrh power. I live on a hill, and in first gear coming up my driveway, it would just bog down and then start jerking. The engine sort of sounded like: bbbwwwaauuuu a real low gutteral sound. Now, it barely starts, and when it starts, doesn't get past 2,000 RPM then just dies. My check engine light is on when the car is off, but when it starts up for the 2-3 seconds the light goes away. About a month before all this stuff happened, I replaced my fuel filter, air filter, new spark plugs, did the fuel injector cleaner thing... Fuel pump is brand new(replaced due to another problem a while ago). Any suggestions would be greatly appreciated...