to get the most out of your xr6 engine you can keep the ea log manifold and use the ed xr6 ecu and fuel reg ..the xr6 engine has bigger valves and different cam so the xr6 ecu will have fuel maps to suit the engine..
than it might be on par with the ed xr6..

or as others have said convert it to the broadband manifold and use a el xr6 ecu...

and use a smartlock overide module..

what the,,changeing the engine only has nothing to do with the diff gears,,the engine don't care what diff gears there are,,,it doesn't go,,oh no 3.23 i can't handle that,,, there is something wrong else where,,could be a buggered ecu or fuel regulator,,unless the diff was changed or the gearing in the box.

i changed my 3.9 to a 4 and had no problems,,i changed the ea 4 speed box to one from an el,,have no problems,,,so it must be somewhere else.

not much homework got done on this project!! should have considered ecu, intake, driveline etc at the start, not afterwards. thats a backwards expensive way of doing things.

as it turns out it seems you don't deserve the car anyway. anyone who tries to run from the cops needs help. you may get away or you may (more likely) kill yourself or some other poor innocent person in the process.