I have engine light on, loss of power up hill hesitation and shuttering while driving, idles fine, good temp n oil pressure is it the fuel pump relay? My fuel pump comes on when ignition is on, Also this problem has occured in the past but not as bad engine light didnt stay on and seemed to go away. I do have the slightest leak in intake manifold gasket but water doesnt even make it to ground and idles great. Hasnt stalled on me, If vehicle is not allowed to warm up going in reverse out of driveway gives loss of power. The loss of power shuttering n engine light happened at end of 200 mile journey ran the tank low filled up drove about 90 miles.