I am working on a 02 cavalier that has no power and hesistates. On the dyno we go to wide open throttle, the car goes to about 30mph in 2nd gear(automatic), and then revs up to 4 grand and stays there. And then all of sudden after about a minute of flooring it, something happens, and the service light(the wrench not the check engine light) comes on and the cavalier takes off. And from that point on the vehicle runs fine untill we shut it off, and then it does the same exact thing. All of the sensors react once the vehicles operates fine. The spark is a little weak all the time(not blue). When it is running rough the exhaust flutters like it is not getting enough gas. There are no misfires detected but it's probaly has an even misfire so there is no crank variation. It's been 3 days and not getting anywhere. Anyone have any ideas?
-Also, the dash lights(except check engine light), randomly come on and off, including airbag lt, highbeam lt, abs lt, stbelt lt, etc while driving and don't seem to effect the vehicle.