2000 Taurus jerking like hard misfire when warms up

I have a 2000 ford taurus flexfuel 3.0 litre my problem is when the car get up to regular operating temprature
the normal range the car will start jerking and shuddering like a bad misfire it will like misfire once and then it will do it like 3 or 4 time in a row real fast when the car is cold it runs fine I replaced the fuel filter sparkplugs and wires & coilpack and air filter new fuelpump too. I bought MAF cleaner in a can and sprayed the MAF sensor and let it dry then pulled the neg battery cable to reset the computer but I still have the same problem the car has 71000 miles
and never had a problem until now it starts fine hot or cold just has a spuddering type of misfire when it gets warm tach stays the same does not bounce up and down only when I first start the car the tach will go up to 2000 and then drop down to 1000 after a few seconds and stays there until you press the gas. Its always done this as long as I have owned the car this spuddering problem started like 6 months ago I could notice a real lite sputter misfire but was nothing bothering about it but it has gotten worse over the past few weeks to where im afraid the car will stall at the intersection. Thanks for any help you can offer