High, rough idle and shuddering at constant speed? Help please!

willandrews · Post by **willandrews** » Sat Nov 26, 2011 2:10 am

Hi all, I just bought my 2003 Vibe GT in August. When I bought the car, the idle was normal around 1000rpm after warming up. Now, the idle is around 2200 regardless of temperature, and it fluctuates a small amount. The engine sounds rather rough all the time, and when driving at a constant speed, the car will shudder back and forth rather violently. I have noticed about a 20% decrease in fuel economy. The IAC motor has been replaced, as well as the throttle position sensor and spark plugs. I'm currently attempting to reset the ECU to see if the car will try to relearn idle. I took it to my local GM dealer and they couldn't figure anything out. Any input, help, or suggestions would be greatly appreciated as I'm totally lost. Thanks!

2ZZGE · Post by **2ZZGE** » Mon Dec 12, 2011 1:58 pm

are you have check engine code?