Ford EA idle problems are common.
The reason for high idle is the base idle needs to be reset, why I’m glad you asked.
The reason why Ford EA start to develop idle problems most of the time it starts with a flat battery, or a battery replacement
Why should this effect the engine idle speed, another great question?
The ECU has a RAM this is fantastic so long as you keep 12 volts supply the vehicles ECU is happy but over time things change
but the RAM holds onto vital information and operates as if nothing has changed
Now when the ECU looses its 12-volt supply so does the RAM then as soon as you start the engine the ECU starts to check all vital information but this time some input values have changed so the result is poor idle speed.
Its known that if the values are within spec the engine ECU will over 250KM correct erratic idle speed, or too high or to low.
This happen to my fathers Car once, so I reset the BASE IDLE and every body lived happily afterwards
How to prevent Your vehicle form poor idle or loosing radio codes
Never operate a vehicle with a potential faulty battery; if you need a battery replacement, this is what you do.
Go to and auto outlet and purchase a 12-volt supply for the cigarette lighter to keep a 12-volt supply whilst changing over the battery
Or if you think this is difficult call a battery man like Marshall’s and ask them you want to keep your radio codes, they should know what your talking about, or just say Darren Said.
Hope this helps