'93 B2200 surging idle.

Does anybody have any ideas what would cause the idle to surge? It goes from 700-1700 rpm at idle when warm. We put a new engine in it during the summer, and It just started doing it in the last couple of weeks.
Thanks

More info please, carb/Fi. Guessing carb but never know.?

More info please, carb/Fi. Guessing carb but never know.?

Sorry bud, it is FI. I figured I would start with the basics like vacuum lines, PCV valve, etc, since there are alot of Mazda experts out there, I am sure there is something I would never think of.
Thanks.

check out avproecu.com i think that is right, they will tell you how to pull codes out of your ecu. start their first and repost. I just had to send my ecu to them for repair my 2200 is also FI (pretty rare).

Will do.
Thanks.