2000 explorer wont run when started cold.

while cranking the engine, i have to hold down the gas, after starting it will die if i let off the gas, and its also smoking blue smoke. is this a mass airflo sensor problem or a throttle body position sensor or what. the SES light isnt lit up either. so i dont know what it is and also its getting horrible gas mileage. its my moms explorer and she cant drive it anywere. so some one any idea's will be greatly appreciated. thanks

possible the oxygen sensor. look at previous post on how to replace it. not too hard but be safe.

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