u/Leather_Ad_9689

Got my 98 GT dyno tuned a while ago and it seems like ever since then it hasn’t idled right on cold starts. It fires right up but then the revs quickly drop right to 900-1000 rpms instead of idling high for a bit while the engine warms up. Is this an issue? Did my tuner do this on purpose? Or is it a coincidence and do I need to clean my idle air control valve?