This is really different!

been a reader of all the forums about "dustbuster" vans and NEVER have seen this one! the other day my APV developed a misfire and went down a cylinder. Got home OK and had to park it for a while.....naturally I began thinking ignition, either a coil pack, plug or maybe even a clogged injector (3.8)....So today i popped the hood and found the problem quickly! A plug wire had been cut ---- BY THE COOLING FAN BLADE! How did the wire get there? That is the mystery! Allthough the wires had been replaced, they were solid in the wire loom and I had not moved anything around.....Replaced wires and plugs and it is all good again.....

Just how much movement is there in the engine and transaxle mounts, anyway? Did this begin after backing up?

Had replaced the dogbone a while back. Best i can figure the wire was cut while moving along at 25 mph or so.

Other than movement or excessively long wires, I'm at a loss.

I've had a plastic fan blade break and puncture an anti freeze bottle but not on an electric fan. You can block the tires and watch as someone else puts on the brakes and slightly revs the engine.

Well...you were not under the hood when it happened...so..... I'm happy you found the problem anyway.
I was to suggest the dog bone...but you changed it already (like I did: it solved a rumbling noise I had investigated for a long time before....and several other members on this and TS forum)).
I know my bottom engine/tarnsmisison supports are severely corroded and even sagging a little; one m,ember on the TS forum had the subframe ruptured 1 or 2 years ago...(looking for the link...) ..so our ageing crates show their age now....all weird things are due to occur...