I have a 2000 s70 with the 2.4 non-turbo. I had it tuned up and a new upstrem o2 sensor installed and had the obd reset. Now sometimes when I'm traveling at any speed sometimes I get a small miss when I ease on the throttle. It feels like lack of fuel to a injector. I can give it more pedal it it seems like it catches up on goes on. It doesn't do it all the time. I was told it could be the air flow device. I took a look at the new ngk plugs I installed a couple of weeks back. They look good. There is no check engine light on. Can anyone help me