Ford Repair: engine idle speed increase, scan tool, speed increase

Question
1992 ford e-150 302 v-8 auto trans.    when engine reaches normal operating temp. idle rpm increases to 2000, check engine light comes on. turn off key, then try retrieve code, it does not indicate any code problem. turn on key/restart, normal idle for approx. 15 seconds, then high idle again, and chech engine light comes on.  any suggestions?  

Answer
Hello and thanks for the question...I'll try to help.
What I would suggest is that you get the check engine light to come back on and when it does..........perform a Key On Engine Running test......DO NOT turn the vehicle off when hooking up the scan tool. See if that works.
Erik