I have a 2009 cobalt with 70k miles. The other day it started to go into limp mode.couldnt go over 5mph and kept stalling. Brought it into my dealership and they replaced my throttle body. And after that all test came back fine. Got my car was running great then it started happening again. However now when it does stall out my gas gage drops dramatically (from full tank to 1/4) any ideas?