my car idles rough when cold. the exhaust smells nice and all watery like it's supposed to within seconds of starting up, but it shakes a little.

I had the exact symptom on my previous chrysler, and was buying a whole bunch of amsoil (tranny & motor & PS & diff oil) and they had special offer going on when they just released Pi "cleaner". so i was like what the heck and bought 2 bottles for extra $10

and... well............... believe it or not it took care of vibration.

none of the commercially available cleaners did that (except techron. i didn't have easy access to that when i was in canada)

now the Pi is $10 + shipping... i'm looking for cheaper alternatives to fixing shaky (is an overstatement but i expect the internally balanced V6 to be silky smooth as if it were off) idle????? morning temp is 50-60F
the Marvel Mystery Oil sounds very cool

hows the "injector cleaner" for friday morning discussion?

 

Look into your motor mounts.

 

I agree with the motor mounts or something else. It's very unlikely it's a fuel system issue. When you first start it while cold, immediately put it in drive for a few seconds, then reverse and see of one has less vibration than the other. If one is significantly worse you have bad mounts. You can still have bad mounts if this does not happen but it's beyond a doubt if it is bad in one direction.