Swapped 4.0's Computer Reprogram?

[Kongslibakken]

Hey Guys I recently switched motors in a 96 Explorer Sport I went from Hydrolocked 1/96 OBDII Motor to a 6/96 OBDII Motor from a rolled Explorer. I fired it up now I have a High Idle 2500 rpm's it runs smooth but when it comes down to 1000 rpms it runs rough. It starts hard after it warms up. Do I need to do anything to reprogram the computer or have I lost a sensor. The code reader shows no codes. Any ideas are welcome. Thanks

[TigerDan]

There should be virtually no difference between those two motors. I would check for vacuum leaks, and check and clean the IAC and its passages (I assume that the new motor came with its own IAC and that's the one you're using?) and it wouldn't hurt to clean the MAF and Throttle Body as well. Be sure to use a spray cleaner designed for cleaning throttle bodies, not just plain old carb & choker cleaner though.

[Kongslibakken]

Thanks I'll give it a try each little step is making things better. Are you in the true part of NorCal??

[TigerDan]

I guess that would depend on what you consider the "true part"... I'm about 2 hours north of the San Francisco Bay Area. Jeg betenke det å bli avrette nord...

[Kongslibakken]

Ikke bry deg som er langt nok nord jeg bodde i Redding og Yreka. I didn't think there were to many of us up there. You should know what Kongslibakken Means

[TigerDan]

I used to live in French Gulch, just outside Redding, but I'm a bit further south now. And I don't actually do too well in Norwegian, I lived in Sweden for a year so I'm a bit more fluent in Svenska. But they're pretty close...