I'm going to have to agree with hydra, but just to throw in a monkey wrench I'm going to suggest ignition (cap & rotor).

 

i dont want to sound dumb here but the 15 cold starts, can i just sit there and start it 15 times to get it over with? also will the cutting out and spitting and sputtering stop imediately or after the 15 starts and 40 to 500 miles before getting better.
to hydroshocker- where is the 02 sensor on the cat,i thought i heard or read there was 2 of them on the cat. thanks to all of you guys.

 

You won't sound dumb, we would rather see some one listen to us and try to learn. No you must drive it not just start it and shut it off, it has to relearn under driving conditions. It will run rough at first as the computer relearns, but should be noticably better with your 4 drive.
As for the O2 sensors, the only two that concern the engine are the pre-cat O2's. The 1 post cat is only there to make sure the cat is still there/working. Find you catalytic converter and trace the exhaust back to the engine. There will be one for each bank of cylinders.

 

does that mean that i need to drive 40 to 500 miles right after i do the other stuff or can this be over days and also can i do the 15 starts all at once. i just took it out and it was backfireing so i punched it for a few seconds and it has been running good since but i havent drove very far.. i did stop and shut it off to go to store and started back up and still running good right now and i still havent reset sensor yet till i find out these answers. thanks allot
hammer

 

I wouldn't just start it and shut it off 15 times. It has to go through the warm up period while its relearning so just turning it on and off will not do much. The 40-500 miles don't all have to be done at once. Just drive it normal for a couple of weeks and it will be fine. But you should reset it after all the sensors you may replace to so that it will relearn with new inputs.

 

to hydrashocker- do you still think that it is the 02 sensor if it does it until i go out and really get after it and then it runs smooth for a while but the next morning after about 5 minutes or less it acts back up again. thanks for your input

 

the 15 starts need to be COLD, once the engine has been started it is no longer considered a cold start, it needs to sit for a while to be COLD

so it will probably take a week or so to get 15 COLD starts out of it.(once in the morning when you go TO work, once in the evening when you go HOME from work)

for the driving just drive it as you normally would, one tank of gas and you should be all set, does not matter how long that takes.

 

I would say that that it needs to start cold 15 times and come out of open loop after it is hot and read the measurements. That is why it can take up to 40 miles plus. I remember one time it took 300 miles to fully relearn on mine.


Sure sounds like it's worth a shot.

One way to see if it is a plugged CAT is to take the O2 sensors out and tie them up out of the way still plugged in and well away from the heat that will come out of the hole. Then take it for a ride and see if it helps, if so then it's a bad CAT, if it runs the same then it is a pre-cat O2 sensor.

You should have a pre-cat O2 sensor on each down pipe coming out of the engine before the "Y" and a single after the CAT. You can swap one and try then if not swap the other to the other side and try again.

 

it is backfiring through the exhaust,i paid attention to it allot more and that is where it is coming from. I bought the 02 sensor yesterday and i am going to put it in today and i will let you know. By the way it ran great this morning when the temp about 47 degrees and didnt act back up till i went home and let it sit for about 1/2 hour and then it ran like crap again if this info helps at all.
Hammer

 

does anyone know how to change front bumper on my durango? it looks like it is going to be a pain