Preventing rough idles and stalling on a Subaru Outback using Sea Foam High Mileage [SOLVED]

Hi. I have a 2008 Subaru Outback LL Bean Edition with a 3.0L 6-cylinder 5-Speed Automatic transmission, 105K miles. I’ve noticed a problem the last couple days where, when sitting at a traffic light, etc., the engine will be idling properly and then the car will suddenly shake a little and feel like it wants…