Sometimes when I start my car and just let it sit and idle the temp. will rise above normal and will act like it is overheating. The temp gauge goes way up, the fans kick on, but there are no other signs. The engine doesnt feel overheated, there is no steam or anything like that and if I shut the car off and let it sit for a minute you can hear a "gurgle" sound and it goes right back to normal temp and everything is fine. ALSO, when I am driving my heat will blow just as hot as it ever has, but when I stop at a light or stop sign or anything it blows cold air. Any ideas where to start? I was thinking possibly thermostat, but I have heard this is rare if the car is overheating. Thanks guys.

air is in the system....theres probably a leak somewhere (cap, overflow tank, etc.). there's a bunch of threads on this but you probably want to take to dealer and have them pressure check the system.