On a wet rainy day my taurus started running rough. later as I was getting off the interstate highway it died and now turns over but wont start. how can I check the codes to find the problem?

before you do anything check you fuel line at the engine and see if you are getting fuel. sounds like its not getting any fuel.

you have a possible vacuum leak somewhere or maybe clogged egr

You will need to figure out if you have spark to the plugs, and if not- if you have voltage to the coil to proceed.

if its fuel injected have a pressure test done and if it has a carb it could be dirty fuel filter but first id check the fuel filter

check for water damange getting or ciols or computer

Check the vacuum hose attached to the fuel pressure regulator under the hood next to your intake pull it off and see if any fuel is present, if there is replace regulator.you may have to tap hose with your finger to get any fuel out or start vehicle run until hot then shut off and recheck if no fuel present in vacuum line let me know and we can try something else.

check the fuel pressure when it is idling for about the time it takes to die see if it drops.most likely gonna need a fuel pump

Damp is getting into your electrics. Spray all wires and disributor with WD40 after wet days or nights before trying to start it. That should cure it

alternator

check the fuel pressure or sounds like mass airflow metter itself