Have you had the lamda sensor and cat checked. I had the same problem with my StreetKA and transpired it wasn't the ECU but the lamda sensor and the cat was knackered. Do not go to Ford to have this done because they want huge amounts of money.

I also had my HT leads changed which also seems to have helped.

Since ditching Ford and my local garage for my current mechanic, many of my problems have been solved but it has been a case of slowly, slowly catchee monkey.

I'll be honest I don't know how to remove the ECUs but I do know a company that if you take it off and send it to them, they will test it and if necessary repair it. The cost of the test is £37.00 plus carriage there and back. They charge £150 to repair the unit if required, which includes the testing fee.

I can let you know the details if you wish.