This sometimes occurs again--stopping-starting- -even after engine has warmed up--also has times when it is idling too high when in park. I also noticed the cataylic convertor making a pinging or ratteling noise
that pinging and rattling maybe something that can clog your exhaust, I know that if anything interferes with the exhaust's flow, it can cause adverse idling. and it highly dangerous to run for long periods of time like that.
