The MAF should be operating during closed and open loop. Maybe they had EEC-IV run backwards from EEC-V.

Your Taurus is slightly different than my f150 but I found this article to walk you thru it.
http://www.shotimes.com/SHO3eeccodes.html And don't miss the 3 parts of the goose test: brakes, gas , & steering wheel.
BE SURE TO HAVE THE ENGINE ALREADY WAMRED UP or you will get a coolant temp sensor codes

If you've never pulled your own codes by jumper & counting the CEL flashes then do the KOEO a few times to get used to it. here is another good sight for walking you thru that and listing the various codes. http://www.fordfuelinjection.com/?p=13
the KOEO can be be done cold, it just reads the DTC'* and doesn't actually test anything.

Another good test is the cylinder balance test. Its for sequential FI. I'm not sure if you are sequential or batch fire though if you have a MAF then I suspect you are sequential.

these are great to know for anyone with an eec-iv

if the light came on then you probably stored a code that you can pull witht he KOEO. theres two sections of codes and that one will probably be stored in constant memory (CM) and come from the second set of CEL flashes

As I stated earlier. I have had a failure with a distributor cap on my old 3.8 as well, which would run like absolute crap until it heated up. When I pulled the cap, I noted corosion on the electrodes inside. Replaced the cap, and presto.

I have also had the same thing happen on the same engine with the MAF being filthy. When I say filthy, I mean it. The Q-tip came out black. The MAF is an easy one to tackle, I would think. As I said before, a simple way to test is to start the car, and unplug the MAF. If the idle changes, you are probably not in the right location. If the car runs the same, the MAF needs some attention.

Either one should be very simple to test.

Beware of the distrubtor housing though.... A chunk aluminum which was the boss for one screw busted off when I tried removing the cap. I had to use a zip tie to hold the cap on after that


*edit* I never received a misfire code when my distributor cap was cracked. I did receive a low/high MAF voltage code though with the MAF. This was all on an EEC-V vehicle though.

That'* why I don't drive Ford cars
Good luck with it.