GOOD NEWS. . . . The PICTURE UPLOAD FUNCTION IS WORKING !!! The tech folks at the parent company have been able to remedy the issue. You can upload pictures once again. Thank you for your patience.
I have a 2000 Cobalt 252 with the engine described in the title. I've had it about a year.
Symptoms: all cylinders appear to be running a little lean - light brown on all spark plugs, idles smooth, strong acceleration and has full power, I notice vibration starting about 1100 rpm until...