Help diagnose...
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Agreed on the coolant sensor and battery. Either and both will cause lots of weird things. The valve spring will cause similar sudden super-bad running but it won't go away. In this case, since it went back to semi-normal to normal, it certainly is not a valve spring. While you are looking at the battery, put a meter across the battery. You should see a minimum of 12.5vdc static with the ignition off. From there, verify the battery connections are clean and tight as well as the battery to starter solenoid connection as that is the electrical center of the car. Don't forget that its electrically hot down there.
