I've been at college and I'm home for winter break and starting to work on my dodge. Before I left I did the plenum repair and a tune up. Ever since then I've had a low idle compared to before I did the plenum. Now in the cold weather, when I start it sometimes it dies. How to I fix the low idle speed? I've checked all my vacuum lines and they all look good.

 

What is your truck idling at? When fully warmed, in gear, mine sits at about 750RPM +/-.....

Check your throttle body.. IAC passage (on the back of the TB) tend to get carboned up, and IAC isn't able to control idle as well as it should. If things look clean, replace the IAC motor.

 

My truck has been idling around 500 RPM in park. I've been searching and it seems that they are supposed to idle from 650ish RPM. I'm gonna take off all the sensors and clean them.

I was thinking my throttle cables may have gotten stretched out a bit? If that is even possible. It idled fine before I did the plenum. I also figured out my overheating problem. The new temp sensor I installed blocked my coolant flow into the intake manifold. The probe on the new temp sensor was longer which caused a poor coolent flow.

 

Air pocket will also give the appearance of over heating.

500 in park is too low. (yeah, thank you mr. obvious..... )

Throttle cable stretch won't affect idle speed. (unless it is too short.... never heard of cable shrinking though.)

IAC is probably the culprit. (on the back of the throttle body. take TB off to clean everything. gaskets are like 2 bucks.)

 

your cold idle should be around 1000 and warm idle of about 600-650. if its not doing this, unplug and replug the IAC on the back of the throttle body to make sure its plugged in right. if that doesn't help, clean the well the pintle goes into. it can get clogged up., there should be a small hole in the end of the well. clean any crap off the pintle. if that doesn't help then replace it. $40-50 at any local parts store.