My FORD F150 did that once after I had the battery removed for an hour or so running some new cabling.
I noticed right away the IDLE RPMs was low but there isn't any way to adjust this with the computerized vehicles. The manual said it should relearn the proper setting but for some reason mine wouldn't do that after a few days.
I ended up having to take it back the dealership and let them reset the idle on their computer for $90 of course.
Don't know if this is your problem or not - It did fix me up ok...
Roy Ken
