For a little over a month, the P0171 (System too Lean) code has been coming up. My brother has cleaned the throttle and the MAF (Mass Air Flow) sensor. It then worked fine for a few weeks, then the code came up again and the sputtering started. He took it to O'Reily Auto Parts. They had said that since the throttle had been removed, it would need to retrain itself. He then tried removing it again, and cleaned out other parts in the car.
Just the other day, my car started sputtering again in the morning. It runs fine the rest of the day. Also, when I was out of town the other day, my car sat for about 4 days with a low tank of gas. When we were traveling on the highway, my reduced power engine light came on. Once I filled up with gas it was fine. I am just trying to see what could be the problem. Do I need a new O2 sensor, a change of the manifold gasket, fuel injector cleaning? Not sure. The car is good to drive, but would like to fix this problem.