I have an 09 cobalt LS, my car is throwing P3000 (CAN data bus, instrumentation - glow plug warning), P0401 (Exhaust Gas recirculation flow insufficient), and a P0128 (Coolant Thermostat, temp below regulating temp) Just repaired a very cracked flex pipe and o2 sensors. When "cold" started it will sometimes stall out, if I clear the codes the RPM's will bounce from 900 down then back up a few times and catch itself but will sometimes just stall out instead of catching itself. I also use to get 30 MPG now get 18! ANY help or ideas is appreciated! Thanks!