Differences Between a 1990 and 1992 4.9L Straight 6?
-The 90 Was an Auto f250 With Ambulance Package
-The 92 is a 2wd 5speed f150

I am curious if there are any differences when it comes to the electronics and fuel injection/emissions related stuff that should be swapped over from the 92 motor to the 90 motor.

 

Differences are a blower motor for the injectors on the 90 was deleted for 92. It's job was to prevent the injectors from heat soaking and shortening their life. That didn't prove to be an issue and the blower motors occasionally started fires so it was deleted.

The starter motor may be different as well. I don't recall the exact year split but the older one may not have the PMGR whereas the newer one will. They're compatible. You just need to run an extra wire to use the PMGR.

Some wire colors may be different. The engines are fully compatible otherwise.