Yeah, this can be a number of things...on my conversion i had a vacuum leak, bad spray pattern on my injectors, and my distributor internals were rusted...After this it was purring nicely. You can easily test all of those, also make sure your timing is right at 0*, if you're using all stock parts you shouldn't need to adjust the idle position screw. Also here's a link to IAC cleaning - http://www.thirdgen.org/techboard/po...221-post6.html