2004 A4 1.8T automatic with stock engine at 50K miles. Alright, I've read all the threads I can about thermostats and coolant problems but I can't quite pinpoint my problem. A few days ago my passenger side heat went out. Drivers side still blows hot. Engine temp gauge has stayed right in the middle. I haven't driven the car really since then. Today I start it up and get a rough idle followed by a CEL. Coolant and oil levels are normal with no leaks that I can see. I'm pretty sure I'm still under certified warranty, but I can't call the dealer until tomorrow. Plus I'm away from home in western Indiana right now and the closest dealer is over an hour away. Any help would be great. Thank you in advance.