It sounds heat related to me.I only know  the1.9 engines. I have heard that
a 2.1 does exist.The hall sender on the left hand firewall has a heat sink
type of mount with cooling fins. this gives the need for cool
running,away.I suspect a short of some kind in the hall sender mounted on
this aluminum holder. Swap it out with the sender in your friends van.If
that is not the culpret,maybe it is the wiring between the sender and the
distributor,or the hall thingiee inside the distributor. Swapthe dist if
the other swap dosent work first.If you want a new ecu, I will sellyou a
used one for only $800.