Alfa Romeo Repair: Alfa idle problem after battery change, alfa 145, volatile memory

Question
I have just had to change my battery.  I have an Alfa 145, 1.6, 1995 model.  Now, at rest the idle rpm is normal.  If I accelerate the engine rpm, and then let go, the rpm drops to about 600rpm, then recovers to normal. The car is drivable, but can stall when driving slowly to a halt.  All I did was change the battery for a brand new one.  I have looked for leaks in manifold pipes but found nothing.
Thanks in advance,     Anthony  

Answer
When you disconnected the battery, the ECM lost its volatile memory--it takes at least 10 miles of continuous driving for the ECM to relearn what is needed.  If this problem persists then disconnect the negative lead at the battery and touch it to the positive terminal for at least 10 seconds, then, reattach it to the negative terminal and again drive 10 miles.

Or, you may have to clean the carbon out of the idle speed motor. Use WD-40, electrical contact cleaner or (with care) paint thinner.