Have your battery load tested and alternator output checked. Go to a Auto Zone or O Riley and they can do this for free and they can come out to your truck and it takes 5 minutes. You don't even have to disconnect anything!

Next I would say replace the IAC and reset the PCM.

 

Just for giggles I decided to take a peek at my plugs as I have had a few rough idles as well. Sure enough the electrodes are almost completely gone. As cheap it is to replace the plugs, I sadly do not have the $20 required to change them as I have no work. :'(

 

ok i went to autozone and they said that the battery and alternator were fine... i went and ordered a new iac and tps. ill let you know in a few days when i get it how it works out.

 

Remember to do the full and correct PCM reset after install!

 

back again . I swapped out the IAC and TPS and unhooked the battery and cranked the car for 30 seconds then reconnected it. It started right up and ran great. As soon as it got up to temp the problem came back. does anyone have any other ideas? Thanks

 

I forget, did you already check your spark plugs? Make sure they are the champion copper core. I'm on my phone right now and I don't want to go back and check things.

 

Back to basics here.... did the truck just start doing this one day or has it been an ongoing / intemittent problem? Did you go back to cheap Champion plugs gapped properly (.040 should be the correct gap but check it)? Are you SURE the TB is cleaned out of all gunk? It's easy to have something lodged in there and not see it.


Other (less common) things to look at would be the cam and crank sensors, although they *should* throw a code. Take a look at the connections on them as well.
Water / contaminant in the tank would do this as well, as would a bad injector.

Gas mileage is tough to judge because there are way to many variables, but yours does sound a little low. Still, that could be bad / soft tires, alignment, driving style, etc.

Is it ONLY after it warms up (temp gauge at half, thermostat open) or does it do it as soon as it kicks down to low idle after starting?

Anything else out of the ordinary happen? Are you SURE the battery is good? Bad idle is a classic symptom of a weak battery.... Not saying anything against AutoZone, but maybe their test wasn't accurate?

Bob

 

+1 Bobman i had a bad battery that they told me was good

 

ok im going to go to a diff autozone and have them check the battery. The plugs are the copper core champions gapped at .040. Ive had this problem ever since i bought the truck, it has just been getting slowly worst. The way that i clean the throttle body is just with tb cleaner and popping the front hose off and getting in there the best i can. It seems to only happen when the car is fully warm. While the car is warming up the idle is just a litttte bit higher and it doesnt feel rough but out of nowhere once its warm it just comes back.

 

AHHHH!!!! I think we may have found something here! Cleaning the TB isn't just from the front air inlet. Here's a link to the full instructions: (Thanks to Hydra for keeping these links updated!)

Cleaning Throttle body & IAC
5.2L and 5.9L
https://dodgeforum.com/forum/1st-gen-...ttle-body.html
4.7L
http://www.mediafire.com/?k0742k5tvj1dqxh

Try that and see if things get better.

Bob