i think you are having the same problem that a friend of mine is having.....we have done all that you have and got no results....today after work im replacing the coolant temp sensor...this tells the computer how hot or cold the engine is.....when its cold the engine needs more fuel than when its warm.....i think thats why it runs good for a few minutes then starts runnin like crap.....i will let you know if this works.....