My 05 wrx is having a really ruff idle, rmps remain constant but the idle shakes the car. Car only has cooling system mods, mitzimoto rad, new h2o pump, ngk titanium and gates racing timing belt. car has 67k on it and mods were only done to because of light hit in front and supports had to be replaced. Has not thrown cel or any codes, and doesn't miss a beat on acceleration. just driving me crazy! Thanks for any help!