Stumbling in the damp. Plug wires? Coil? (864Q)

["Dean and Heather Sutherland" <hsutherl@nbnet.nb.ca>]

My 864Q (approx 170,000km) has developed an off-idle stumble when its wet
out.  Mechanic says probably need plug wires (very possible as they are the
originals) or he said a weak coil could also cause such a thing (that one
surprised me a bit, but OK).  And so, the questions haunting me are 1) Can
you check a coil (or wires for that matter) to determine which it might be
2) Wires for these suckers are more expensive than I was expecting.
Specifically, you seem to pay a lot more for the set that comes with the
loom, which from looking at my motor seems to be nothing more than a plastic
tube the wires run through.  Is this thing even necessary?  Besides, I
always thought wires should be routed away from each other (hence looms) yet
this factory loom or tube seems to do just the opposite by clustering them
all togther.  To loom or not to loom.  3) To order the correct set, it seems
I need to know if the distributor cap has "pins" or not.  Maybe if I
describe what I've got, someone could tell me if this is a "pin" type cap.
Basically it looks like any cap I've ever seen with towers to accept the
wire boots, & if you peer down inside the tower, there is a small (maybe 3mm
long) contact or "pin" I guess that receives the wire contact.  Sound like
the "pin"style to you? and finally (geez why do I obsess about these things)
4) the coil (at least with my local supplier) is pricey.  I'm thinking, what
is so special about this coil, would not any 12V coil do the job?  A humble
thank you to the listers for indulging my curiosity.