2002 Chevy Impala 6 cyl Two Wheel Drive Automatic 125000 miles
First engine would hesitate. It was the catalyst converter. I got that replaced and while I was doing that I changed both O2 sensor (the 1 in front and the 1 behind the converter). After that the engine light came on.
Thats when I got the code P0135 Oxygen Sensor Heater Circuit Malfunction (Bank 1 Sensor 1). I checked the fuse to the sensors and it was good.
After this I took it to another mechanic he said that it might be the MAP and the Air Flow Meter(MAF).
Let me put that in the morning when I turn it on when the engine is cold and Im waiting to warm up. The RPMs go up to 2RPMs and goes down to.5 RPMs almost wanting to shut off.
What should I do next or what do you think it is?
Actually, the O2 sensor could be causing the problem. The one you replaced should still be under warranty, so I would switch it out with a new one. As far as the Mass Air Flow (MAF), it too could cause an idle problem, but so could an idle air control, throttle position sensor, vacuum leak. My concern is that the mechanic starts throwing parts into the vehicle that are not needed. If the computer is saying the HO2 sensor (bank 1), that is where I would start expecially if the part is under warranty.
As far as the Maifold Absolute Pressure sensor (MAP), usually they will kill the engine rather than just cause an irratic idle.