wierd starting idle problem

[pdr510]

I have a 2002 7.3 that has just been rebuilt. It is way to slow to start. Once it starts it has a rough idle. Then when you give it some throttle the throttle response is way too fast. If you let it run for a minute the rough idle will go away and then the throttle response will return to normal. The check engine light will come on while the throttle response is too fast. Then it will go out when throttle response returns to normal. I have tried to pull the codes with a cheap scan tool and it says no codes. Anybody ever seen anything like this?