There isn't a modern computer / tester that will work with the Capri.
You can use the internal diagnostics - jumper a plug underhood and it will flash the Check Engine Light with a pattern that can be easily decoded, to see if the ECU is unhappy with anything.
Ford had a Special Service Tool, that plugged in place of the car harness & ECU, that you could pinpoint test any sensor or ecu output, but they are rare and require specialized knowledge to be used. (you would need to manually test each sensor with a multimeter/oscilliscope, the tool just gave you a convenient set of test points all in one place) The electronics tech dates to the late 80s, early 90s - before On Board Diagnostics were standard - It was 1996 when OBD-II was federally mandated / standardized (the current onboard diagnostics standard) Just to reiterate here, and for anyone doing a Google search in the future here: there's no way to connect a modern scanner / scantool / engine analyzer to the ECU to see whats going on.
The N/A capri are now notorious for cracking the intake tube between the throttle body an VAF meter, pull & inspect, especially underside. The vacuum leak issue persists anywhere behind the VAF - not just behind the throttlebody (hard to test for with smoke machine)