I have a 1994 Escort 1.9L with 142,000 miles. When the engine is cold,
the idle "hunts" up and down. When it's warm, it's steady. However,
when I decelerate and come to a stop (clutch in or in neutral), it
hunts again 5 or 6 times before smoothing out. When the a/c is on, it
dies on deceleration.
I suspect the idle air control valve. When I unplug the electrical
connection to the valve with the engine warm, the hunting stops though
the idle is a bit rough. If I unplug the valve with the engine cold,
I know the valve is responding to the computer which is using info
from various sensors. Before I change the valve, I wanted to see if it
might be one of the sensors.
I changed the oxygen sensor but that made no difference.
There are no stored fault codes.
Any ideas? Thanks!