Help needed. MK1 2004 C Max starting problem U1900

[Hawksey]

Dear all,
Hello I'm after some help if possible. I have a MK1 2004 C max 1.6 petrol and I've been having intermittent problems with starting. It seems to happen more when I've used it on several short journeys into town during the day. It starts fine and then after a few stop and starts it won't fire and takes a good couple of minutes to get going. No real smell of petrol present. So far I've serviced the car, changed plugs, change coil pack and leads for a used tested part, changed T Map sensor, cleaned throttle body and cleared the PCM. It went okay for around a week but problem started again. I've used Forscan to identify the problem and the only fault code is U9100-20
I've read this may be a communication problem caused by the instrument cluster / dash but I can't see how this would effect the car starting. Any help would really be appreciated.

Many thanks.