dont go replacing parts if you cant figure out the problem- its more trouble than its worth. try spraying brake cleaner or some type of flammable parts cleaner around your intake manifold and vacuum hoses, and see if your idle picks up. if so, isolate the problem to a specific area (i.e intake mani. gasket, leaking vacuum line, etc.) and try removing your iac and cleaning it out in a parts washer. (dont use the brake-clean b/c it can eat up the seals inside of it, and make sure to let it dry fully before re-installing it). while washing the iac, use jumper wires and a battery to cycle it and get all the grime out of it- if jumper wires and a battery arent moving it easily, you found your problem. dont forget- iac's are on a duty cycle, so they are kicking back and fourth pretty fast- just b/c its moving doesnt mean its working right.