2003 Ford F-150 idles rough

I have a 2003 f-150 and when I start it up it goes
right up to 1,500 rpm then it comes down under a 1,000rpm and after about 20 to30 sec it starts to run
really rough most of the time stalling. Other than that
its running fine I replaced the air, fuel filter change the oil I was told it might be sensor or two going out
or my fuel injection needs serviceing