ive had loads of xr2i's.
There are a few different types of ecu, Ford had a recall on the earlier 1's cos of a faulty idle speed control valve and if you has it on the bulkhead than it has been recalled at some point in its life!
That means they changed the ecu for a different 1 so the ecu's you hav tried may not be compatable. same goes for chipping them!
I bought a chip for 1 of mine and it made it run well shit but the same chip worked on 1 i had a little while later.
Just make sure you are using the correct bits and pieces mate