1999 Taurus rough idle missfire

Enter your question. PLEASE HELP
I HAVE NO IDA WHAT WRONG EXCEPT MABE THE IAC

at idle car misfires, runs rough and real low rpm IDLE(300-500)
at high rpm car runs great, but trottle sticks 2000 and 3000 rpm)and slowly real slowly goes back to idle. No power if I try to put in gear, just cuts off

at idle it acts like the timming is off. But it's all controlled by the computer, and crank position sensor. NO DISTRIBUTOR ON THIS MODEL CMP SENSOR IS A HALL-EFFECT SWITCH

PLUGS WIRES AND TIMEING HAVE BEEN REPLACED. STILL THE SAME PROBLEM




THANKS