I am just wondering about the general idea. So, when I do not have any gear put in and increase the revs to let's say 4000 rpm and then remove my foot from the gas pedal the revolutions go down rapidly then seem to stall for a tiny bit at certain revs (I think at ~1500 rpm) and then continue to drop to idle at a visibly different rate. I realize the engine slows down when no fuel is fed for obvious reasons, but clearly there is a pattern in this behavior.
In my car (Fiat Barchetta '95) there is a cable connecting gas pedal to the throttle and there is a throttle bypass via the idle control valve (ICV). I am assuming that when I remove my foot from the pedal the throttle closes down almost entirely (right?) and then there is this ICV that might let some air through and adjust engine rpm. I would really appreciate if someone could share his thoughts on this subject.