Having issues with a 90 2.2 not firing on bottom coil. So far i replaced the plugs and wires, no change. Replaced the coil, no change. Then after running a bit it started firing again. Test drove and everything was good. Next day back to not firing. Replaced icm with new ac delco. Still not firing. Cylinders 1,4 are cold and i can smell raw gas from exhaust. I even tried swapping ecm and no change.