Ford: 1999 ford taurus, ford taurus, 1999 ford taurus

Question
99 taurus, 88,900 mi, 3.0L DOHC V6, Just today developed rough idle, rough enough for engine to die at stop light, panel lights dim in brightness in sync with tach drop.  Possible wipers came on (sounds crazy, but maybe I bumped the button...).  Very clean under hood, nothing obvious to me for what is wrong.  Any diagnostic help much appreciated.

Answer
First thing to check is for check engine light...  did it come on? (It'll say like check engine... service engine soon... something like that...) if it did we need to try and get the codes out of it... second thing is to check the alternator and bettery...   and third try tapping on the idle air controller (should be located on the throttle body and has a 2 wire plug going to it...)  let me know wha thappens after this... thanks!