2008 Jeep Compass - Check Engine Light came on; checked codes and replaced crank position sensor. Light went out for about 20 miles, but engine was coughing and sputtering, sometimes so badly that the Jeep would hardly pull itself. Thought maybe it was bad gasoline, so put a bottle of Startron in it. Drove short trips locally (didn't want to break down far from home) for about 200 miles, then put new gas in. Had it in the shop(my son does all my work at his own business) for the replacement of the front subframe, and the check engine light came back on. Unfortunately, it's not showing any codes when put on the machine. It's still coughing and spitting like it doesn't want to run, but I don't know what to check next since the codes aren't showing up. I'd welcome any ideas or suggestions based on your own experience with this 2.4L engine in the 2008 Jeep Compass.