Ok I'm having a recurring problem with my 99 Sable with a Tec. Whenever I come up to a stoplight, the car chugs while I'm just sitting there. It does it in park, reverse, neutral and drive so I know its not a transmission problem. I just replaced a vacuum hose and PCV valve. I dont know what else it could be and its annoying! It doesnt die anymore like it use to but it will drop 100-200 rpms and go back to normal and repeats this in short intervals. No codes from this. Any ideas?