Bouncing idle

[Jack08520]

At cold start she fires right up - idles steady for about 30sec - and then goes through this weird "bouncing up and down" for about 15sec and then smoothes out. Once warm no issues. I did buy an Idle Air Control valve - will this do the trick?

 

[Jack08520]

It was the upstream O2 sensor - had 130k on it and I was also showing P0171...