I thought I would close the loop on this item. I did not have time to get the throttle body cleaned or have software downloaded. I had a wedding to go to in Wisconsin. We left Alabama just before the 4th of July holiday and proceeded North. Usual surging but the car ran fine.

We get to Wisconsin and it is one of the hotter days (90 - 92 degrees F). Just as we left the rehearsal party in the afternoon the engine check light came on with the message emission system check required.

This is the 4th of July and nothing open. We get to my parents home and the temperature that night and the next day cooled off. The light did not come on the next morning. The check engine light stayed off while we went to the wedding and then up to Minneapolis MN. The days were wet and cool. We proceeded to come home and it wasn’t until around Southern Illinois that the engine check light came back on with the same message. Of course we were going south and the temperature had climbed up into the 90's. It stayed on all the way back to Alabama. I decided to take it in and when I started the car the check engine light was off. It was morning and the temperature was cooler. Took the car in and they proceeded to tell me that the throttle body needed cleaning and that I needed to have software downloaded. They could not complete the job until the next day so that was when I picked up the car. I could not get into the dealer until about noon. They had checked it out and it seemed to be performing correctly. I proceeded to go home about 20 miles away and by this time the temperature for the day had started to climb into the 90's. I did not get home before the check engine light again came on and when I slowed down I could feel the surging trying to come on. I did a turn around and went back to the dealer.

They had found before that the Mass Air was reading high so replaced it and took it for a test drive. Still had surging but the numbers were reduced. To make a long story short they ended up replacing the throttle body and the Mass Air.

I talked to them about this condition and they have seen it where the cleaning helps along with new software, then it just may be the Mass Air Sensor and then maybe the Throttle body. They have had cars come in at 10,000 miles but most of them come in with 50,000 plus and out of warranty. There seems to be a correlation between the Mass Air and Throttle body along with outside temperature. More observations may be required but I hope I am not one of them for a long while.

Side note, my extended warranty covered this whole thing. They stated that the total bill would have been over $900. Hope the new throttle body lasts longer than the old one.