ablack934doorcivic

just finished the swap while in my garage the car turned over fine i just wanted to start it up to make sure it ran ok for a min or two. then brought it outside filled it with a little anti-freeze just so it wouldn't overheat while i ran it for a bit to make sure it was ok. that's when my idle would fluctuate between 1000 rpms and about 2000 rpm any suggestions whta it could be