Check engine light-rough idle(Evap plug fault?)

[DangerRanger95xlt]

I am having a problem with my 95 ford ranger. It's an xlt and has the 4.0 v6 and is a 5 speed. My check engine light has been on and it comes up "Evap plug fault" when i plug a computer into it. The truck also has a tendency to have a rough idle(fluctuates) when I pull up to a stop sign, etc. it'll drop to about 500 rpm. I was wondering if you guys had any help you could give me?

 

[RonD]

What is the code number?
Some have different meanings than commonly posted

For EVAP have a look here, there are pictures:
http://www.therangerstation.com/forums/showthread.php?t=89253

Might be related to idle issue but might not.
Fuel injected engines can't use an idle screw like a carb did, no jets, so they use a controlled vacuum leak called an IAC(idle air control) valve.
Computer slides this valve to allow more air(higher idle) or less air(lower idle) into the intake manifold, so "controlled vacuum leak"
The IAC valve can get dirty and sticky causing idle issues, but it is easy to remove and clean.