you may be able to just clean the iac instead of replacing it just pull it off the back of the intake manifold and spray the screen with a carb cleaner or fi cleaner. You can also try to tighten the FITV its on teh bottom of the t-body and has a brass plate on each end. I cant remember which end you need to remove but when you take it off you should see a white piece of plastic in the middle and a big screw like piece on the outside of the plastic piece. You can push the plastic piece down and take a large screw driver or more likely a gasket scraper to tighten the screw like piece down. To detect a vacumn leak if you dont have a guage you can take a propance torch turn the propane on but dont light the torch then run the propane along your vacum lines if your idle goes up then youve found where the vacum leak is. Also you might have air in your coolant lines bleed your coolant. If you do have air in your line youll need to figure out how it got in there cause a blown head gasket could be a possibility. If you suspect a blown head gasket check your coolant if its milky (oil and coolant mix) then youve got a blown gasket. Honda idle problems are a bitch.
Robster