I had noticed a bit of a “throb” through the car at about 1800rpm and had suspicions of a misfire even though at tick over the engine showed no signs of a misfire. After plugging in my code reader out came a reading MISFIRE and a code P0353.
The ford explanation I found was very technical but it appears that the ECU will shut off the fuel injector at speed to protect the cat from unburnt fuel – which seems to be happening with mine. The website I found below was better at explaining how to investigate and rectify the fault.
The PCM sets an ignition coil control circuit code P0351-P0358 when it detects a problem with the ignition coil circuit. The last digit of these codes references the cylinder where the issue is occurring. For example, P0351 indicates a fault in the #1 cylinder coil circuit. Likewise, P0358 indicates a problem with the coil circuit on cylinder #8.
More about DTC codes at …… https://www.troublecodes.net/pcodes/p0353/