While recently driving my 2004 Jeep liberty it started to have idling problems. We were stuck in traffic on the interstate and as we came to a stop the car acted like it was going to die, but it didn't. The RPM's just dropped to like .5 then went back to normal. Later, when we stopped at a red light it did the same thing again. It doesn't always do it, just sometimes. It has now been happening off and on for the past couple of days. Please let me know if this is something serious or something that can be easily fixed. Thanks