I am having the exact same problem. I have a 2002 AU series II 1 tonner auto. I have changed the plugs, coil pack, fuel pump, fuel filter, had injectors serviced with new o rings etc, new air filter and taken it to an ex Ford technician whom is very familiar with this model and he's stumped. He changed out o2 sensor and I think map sensor. He's telling me I need a new engine. The problem is intermittent. some days it will cruise around all day, no problems but usually after a highway run it will run like a bag of sh*t, idle really rough at about 400-500 rpm, sometimes stall and spew black smoke. Then it goes away! All this with either aircon on or off. Never gets overly hot, needle sits between the "O" and "R" in the "NORMAL" range regardless of the ambient temperature. I am losing coolant very slowly but no oil in coolant and no coolant in oil. Otherwise, when its running good, it is smooth as silk, lots of power etc. WTF? PLease help!
