Cecil,

You're on the right track. The place to start is getting a known-good
volt-ohm meter. Then, use your Bentley to do the ECU pin test--you can check
every electronic component of the FI system (except the ECU...) from there,
including your idle switch.

If the pin test shows everything is ok, move on to vacuum leaks. Fill the
engine with air from a compressor and squirt soapy water all over the place
(engine not running.)

Got the vacuum leaks done? Check fuel pressure at the test point.

Once you know that's ok, then do the flow test for the injectors per Bentley.

Doing these tests will point out 99% of the causes of running rich. Note
that the cost, including buying a fuel pressure gauge and a new VOM from
Radio Shack, is less than $100.00. And just think of the fun you'll have!

Another freebie you might try. There's a little green wire that goes from
your ECU to your O2 sensor. It has a coaxial ground on it that sometimes
gets messed up and contacts the hot wire from the sensor. If this is the
case, it will eliminate or severely screw up the signal to the ECU, which in
turn will make the van run crappy (and rich). This defect WILL show up in
the pin test described above, but you might want to just take a look at it
as it's such a common failure point. Even one tiny strand of that coax will
mess things up big time.

The one electronic FI component you can't test very well with your VOM is
the AFM. Do everything else first, then, when you know it's all good, take
your van to a good mechanic with a sniffer. To set the AFM takes about 30
minutes or $50 of shop time. Make sure they set it both at idle and at
speed, like 2500 RPM.

There are other things that can go wrong, but I think this covers most of it.