When I first bought the truck, I had a really bad vac leak (blown plenum) that was causing rough idle. I fixed that about a month and a half ago, and it was idling great, about 700 with just a little bump on the tach. Well, now it's idling at about 900-1000 with the occasional drop down to about 700. I don't think it's a gauge problem since you can hear the motor rev up and down. I don't think it's a vac leak (I can't hear one), so is it the Idle Air Control?

sgg93