I drove my car for 20 min and I noticed that my temp guage wasn't working. I stepped on the gas kinda hard and noticed that it jumped a little and went up to a little under half way which is normal. After a full stop, it went all the way down again, and then I gased it a little and it went back to normal. Also, when I gas it, the temp needle moves a little. I turn the car off and back on, it is working normally now. Do you think it is the O2 sensor that is loose on the downpipe? When I took my car to a shop yesterday to extend the downpipe, this problem happened. They did use a new gasket. Any ideas?