2005 freestar driving down the road suddenly starts stumbling rpms drop and emission light comes on then dies. Scaned it but says nothing is wrong

Give it up and have a dealer look into this problem.

fuel filter,coils module.

if its a 4 wheel drive it may b the trnsfer case

you did not give a trouble code from the check engine light, but probably a Vacuum leak.

A faulty egr would not create a high idle issue. if an egr valve were to open while idling then it would create a heavy stumbling engine or it would die right out. if there is a check engine light on (or service engine soon light) have the codes pulled. Failing that then I suggest taking it to a reputable shop

sounds like the alternator is going bad. I had the same problem in a 94' Ford Probe. I replaced the alternator and it ran perfect. Hope this helps

Hmmm, this is very strange. I have two articles that I have read that come to mind that I believe will help.

It sounds like this happens all of a sudden when driving given that the speedometer and RPM go down, you say, and for this, please review the following article that addresses the possible causes of your engine's abrupt/sudden dying while driving at this link:

http://yourhandymanzone.com/Your_Handyman_Zone_How_To_Pages_Vehicle_Car_Zone_Cars_Trucks_Vans_Engine_System_Engine_Abruptly_Quits_Periodically_While_Driving.htm

Also, since your gauges go down while driving, in addition to the probable causes mentioned in the article linked above, your problem may be a bad alternator according to this article on the sudden loss of a gauge reading while driving:

http://yourhandymanzone.com/Your_Handyman_Zone_How_To_Pages_Vehicle_Car_Zone_Cars_Trucks_Vans_Alternator_Gauges_Go_Up_And_Down_Like_Crazy.htm

These articles should lead you to a solution.

A sudden drop in "rmp" like that is more likely a spark problem not a fuel problem. I would suggest a crank or cam sensor peoblem. Good Luck

you may have a vac.hose leaking some were on the motor

the switch is going bad it is on the latch itself