Agree with disconnecting the battery for a few minutes. Its a quick fix.
Im def no mechanic, but work on all my own cars with success and disconnecting the battery clears the vehicles memory for me..
And can tell you on your focus that you can do this (disconnect for 30 min) and clear it, the car will naturally over time relearn its idle and fuel trim strategy for optimum drive-ability and performance.
There is also a step process located in the focus owners manual that you can do to force the car to clear and relearn.
Taken from the owners manual of the Focus.
Because your vehicle’s engine is electronically controlled by a computer, some control conditions are maintained by power from the battery. When the battery is disconnected or a new battery is installed, the engine must relearn its idle and fuel trim strategy for optimum driveability and performance. To begin this process:
1. With the vehicle at a complete stop, set the parking brake.
2. Put the gearshift in P (Park) (automatic transaxle) or the neutral position (manual transaxle), turn off all accessories and start the engine.
3. Run the engine until it reaches normal operating temperature.
4. Allow the engine to idle for at least one minute.
5. Turn the A/C on and allow the engine to idle for at least one minute.
6. Drive the vehicle to complete the relearning process.
• The vehicle may need to be driven 10 miles (16 km) or more to relearn the idle and fuel trim strategy.
• If you do not allow the engine to relearn its idle trim, the idle quality of your vehicle may be adversely affected until the idle trim is eventually relearned.
Like I said its in the owners manual.
Not an ASE CMAT/L1, and dont need to be.
then since you disconnected it, there is something still wrong or not properly installed. did you go for a drive/s??