Scott2112

I am a stone cold newbie and this is my first post, so if I violate some sort of rules please forgive. My name is Scott, I drive a bone stock 1996 200sx ser, w/ an automatic tranny. I take very good care of my car, I am a excellent shade tree mechanic. I have owned the car for a little over a year, and when I bought it, I flushed the tranny, changed the the tranny filter and added new plugs. Recently I have added new plug wires, cap rotor air and fuel filter and radiator flush, I verified the thermostat is working. The problem is this: once the car is driven for about a half an hour, it idles erratically and when I put my foot on the brake at a stop light, the engine will die if I don't shift the car into neutral. The car will idle fine in my driveway for over an hour, but once i put it in gear, it will start idling erratically again. I have taking it to the local autozone and they told me it was the knock sensor, they cleared the code and it ran fine for an hour, then it started again, the local mechanic set the base timing, it ran fine for an hour, and started back up again, can somebody please point me in the right direction???? this broke college student and former marine thanks