My car is a 93 240 wagon AT with 151k miles, driven daily.
My bizarre problem is this: The car seems to idle well, but maybe every 2 or 3 days it will stall very abruptly while idling at a light, but then start again easily. The car also has a very intermittent 'Hiccup' in power while accelerating. Its like the power is there, then it stutters (cuts out) once or twice for a half or quarter-second, then accelerates normally again. It's very unnerving, especially while merging onto the highway. The really strange thing is, the intermittent stalling has now apparently also caused the check engine light to come on three separate times, for three seemingly unrelated reasons. I have checked the codes that caused the 'Check Engine' light to come on under the hood, each time, using the chart in the Bentley service manual. The first time the light went on, the code told me I had a fault in my O2 sensor, which I replaced. The car ran smoothly for a week or so, then it started stalling / hiccuping again. Same symptoms. The Check Engine light came on again, and this time the code told told me I had a fault with my coolant temperature sensor (even though i was still geting a temp reading on the gauge). I thought this was strange, but replaced the sensor with a new one, unplugged the battery to reset the light, and all seemed well again - for another few days. Today the light came on again, and the code is now telling me '1-1-1', which apparently means the system is working properly and nothing is wrong, but yet the light is still on and the idle seems a tad rougher.

I went through the Bentley troubleshooting list when the intermittent stalling/stuttering first began. The plugs are good, gapped correctly, not fouled. Cap, rotor, wires and coil are all less than a year old and in good shape. Oil is new, and the car doesn't burn any or leak anywhere. The fuel filter that I just replaced was nearly plugged, but a new one didn't help the problem. Air filter is also brand new. I'm out of ideas. Could these symptoms be a timing belt/tensioner issue? A computer problem? Could one of these cause check engine light problems? Prior to when the car first began stalling around a month ago, the car had run absolutely perfect for over a year. Any thoughts/ideas would be greatly appreciated!! Thanks!