I agree, $600 is WAY too much. Around $300 would be reasonable because the Aerostar
is so difficult to work on, considering dealer labor and parts. Being a woman may make
a DIY repair easier, as your hands and arms may tend to be smaller than the average
gorilla male technician. ;)
 I did a quick search for manuals on Ebay. There are a couple of paper EVTMs
(Electrical diagrams) but I didn't find any of the main service manuals in paper form.
For a complete set there would be 3 books (EVTM, PCED, and Volume H). There are lots
of CDs though, and they cover all of the material in the 3 books. The Ford service
manuals have been available on CD since 1992. They take a little getting used to but
are the same info as in the paper manuals. Here's one:
http://makeashorterlink.com/?K24352ADD . This is a (possibly illegal?) copy of the CD
used in the dealerships.
 To do the tune up may take up a weekend the first time if you havent attempted to
work on your car before. It would be good to have a knowledgable friend for backup.
With the proper tools, as mentioned earlier, it should cost ~$120 using good parts.
Use Motorcraft plugs and good (~$70) plug wires.
Good luck.

$600 is a lot for that; it should be $300 or less for plugs, wires, cap
& filters. If you want to try it on your own, get the FACTORY Shop
Manual from eBay (used) or from www.helminc.com (for new). You should
also have a set of socket & open-end wrenches, a test light, a torque
wrench, and a code reader. The first thing I would do is put in fresh
spark plugs, which go a long way toward helping a car start. Another
design weakness preventing a quick cold start is the Idle Air Control
valve that wears out over the years & miles.

my problem is that on some days my van wont start so im thinking
distributor cap. now i took it to a repair shop and they said that was the
problem and also i need a tune up and wires and they quoted me $600.00 to
put new wires and new cap and air filter and fuel filter so my question is
$600.00 to much to pay?.and is there any way i can do it myself with a book
or anything else. by the way i am a woman could that be why the price is so
high. please help.