High idle when starting .Than it goes to 1000rpm . Have ck engine light on also.

You did not indicate which engine is in your Bronco -- the 5.0L or 5.8L V8 were choices. Either way you look at it, diagnostic testing on this OBD-II vehicle is needed. Diagnostic trouble codes will give you clues as to what directions to look into. On the surface, I suspect an air intake leak of some kind, causing air to get into the engine unexpectedly, causing the engine's processor to call for more fuel delivery which will raise the idle speed unnecessarily. "The only thing I didn't change" -- don't change parts without testing or verifying a part has failed. That's an important recommendation. www.repairpal.com/repair-shops