ok, here is a new one:

thought everything was fixed ... it was running great! Then, I washed
and detailed the engine. We drove around, and everything was fine. After
being parked for about 30 minutes, we got back in to go back home. The
van started hesitating, to the point of not moving. We turned it off and
on several times and it took us home... about a couple of miles driving
on and off. Towards the end, it worked fine. We parked, turned it off
and on again, and I heard a clapping noise from the black plastic box
(where the 4-pin connector plugs in) on the Intake Air
Sensor/AirFlowMeter (025 906 301 C). As the flap that is inside was
abruptly snapping on the housing or a bad electrical spark in that black
box.

We are letting it sit for tonight and see what tomorrow brings.

Any thoughts, suggestions on that?