I have a 2001 Taurus with the standard SOHC 3.0 engine. I had the famed egr sensor (P0402 error code) go bad last year.
When that happened, I had the local dealer do a diagnosis and they listed a ton of things that needed changing (110,000 miles). I changed the egr sensor, but ended up with a generic that didn't have the same voltage range and had to get one directly from the dealer. This fixed P0402.
However, in the process, I replaced the plugs, the wire and the idle air control valve. Now, the car idles poorly and sometimes stalls at idle - especially at redlights or when stopping going up a hill. If I let it idle for about 5 minutes or so, I will get a P0300 (random misfire) that disappears if I drive the car around. I switched all of the items back to the original ones and that didn't help, so I put the new items back in/on.
Can anyone offer a suggestion? Why would the idle start acting up all of a sudden after changing the plugs, wires, and idle air control valve and not work well when I put all of the old items back in?
Oh yeah, I almost forgot, I have also replaced the mass air flow sensor.