This is my first 3.9. Its in a 1/2T cargo van, 1997, with 35K miles on it. Yes, that is correct, 35K.

The vehicle runs great. No hesitation off idle, good power for a V6, runs smooth. At idle, it has a slight vibration or shake. It doesn't seem like its a fuel problem. I'm used to the smooth silky V8 idle. Is it just the nature of the V6?

 

No, it should be smooth at idle. Under-driven vehicles are prone to additional carbon build up. Have you pulled any spark plugs to see their condition, or looked under the cap for signs of corrosion?

 

If it's carbon build up and related to the idle, cleaning the IAC and it's port would help. https://dodgeforum.com/forum/dodge-r...n-the-iac.html

I just cleaned my son's 91 Firebird IAC. He thought I was joking that his car had one because my van is a Dodge. The car has 150K on the odometer. We broke off the two nuts holding it on. After boring them out, the IAC cover plate on the 3.1L easily came off. WOW, there was solid carbon all in the IAC chamber. The IAC had no place at all to travel.

The torx nuts on the Magnum engines should come off easy, unlike the Firebird.

 

Mine idles a bit rough,too. I've also had a '00 Dodge Ram 1/2 ton with the 5.9 that idled the same way as well as a '07 Hemi quad cab. A buddy of mine who was a Dodge mech. said the mfr leans them out to pass emissions and that it's normal.