Rank: Guru
Rating: 93%, 316 votes
It sounds very likely that it is going lean. Could be a bad Mass airflow sensor or a fuel pump, maybe plugged injectors. The first thing to do if you can get your hands on one, is to put a scan tool on it that reads live data and go up a long steady hill while you are watching the O2 sensor voltage. It should toggle back and forth across .5V, if it remains below .5V while you drive, then you know it's not getting enough fuel. If so, check the fuel pressure to spec. If it is good, then the pump is fine and you're chasing the other two.
