New Cobalt SS owner
I recently purchased a 2007 Cobalt SS. I have been working through some issues. New shocks/struts all the way around, new front wheel bearing, sway bar links, brakes and rotors. IT doesn’t like to idle. If it tries to idle around 850-900 rpm it will surge up to about 1400 rpm. It goes through this cycle of up and down about every second. I removed the factory exhaust system and replaced it with a ZZPerformance exhaust, 3” from the manifold to a 2.5” the rest of the way back. This helped the idle significantly. Now I am only experiencing the surge at idle 20-25% of the time. The inter cooler pump isn’t working (new pump on order). I have not been able to find any vacuum leaks anywhere. Other thoughts?