Recently I have added hooker catback, eibach prokit, KONI SAs, MTI lid, K&N filter, port/polish/descreen MAF, and SLP smooth bellows. About a week after all this was done my SES light comes on and now all RPMs are about 500 lower than normal, idles at 500-600 instead of 1000, 60mph used to be 1850rpm now 70mph is around 1850.

Any ideas what could cause this?