VOLTAGExDT

First I am somewhat of a Noob. I am mechanically inclined, however when it comes to what this or that might be or what causes this or that. Ya im a noob.
And thats why I am here.
My issue is that i also have a very rough idle.. truck runs great but at idle it seems like its misfiring, and if im coming to a stop and engage the clutch 30% of the time it dies out.
What I have done so far.
Cleaned out carborator (if thats not what it is please give me the proper term or name) using carb cleaner
did a full tune up:
Cap, rotor, plugs, air filter, and plug wires
Today i was told to try the o2 sensor.
So i went to take off the o2 sensor to bring it with me to auto parts store (so i get the right one) and there wasnt even a wire on it.
Now i dont mean to say it was un plugged. I mean some one cut the wire off of the sensor completely.
Furthermore the wire is no where to be seen.
So i re-ran a new wire from the ecm to a brand new o2 sensor.
Still same idle issue.
91 Chevy K1500
5.7 v8 Manual
One final note..
There is a tube that runs from the vapor canistor (i think) to a sensor or solenioid.. and out of that it runs to under the carb.. now this sensor or solenoid seems to have had a plug in at one time. but again it has nothing plugged into it at all, nor is there a plug to be seen.
Thank you.