Toyota Repair: misfire, wd 40, ascii mode

Question
I have a 1989 Camry 4 cyl. with 150K miles.  Have never touched any of the fuel injection parts so far.  It ran fine yesterday - this morning it has a misfire. Replace all plugs and fuel filter.  Checked and all spark plugs (with light) and all firing.  Really shudders under acceleration then somewhat smoothes out.  Can feel misfire around 2500 RPMS then kicks in and out.

Answer
Lane,

 Thanks for the specific information, most of the time
there isn't any.

 If I was at the vehicle I could quickly
find the problem, but we don't have that luxury
so we must work in LDAM (long distance ASCII mode)

 First, Remove all plug wires and closely inspect
wire and the boot for cracks. I've seen cracks
in the spark plug boots and under a load (acceleration)
the spark will jump to ground.

I would inspect all components of the distributor,
rotor, cap, and look for oil in there. The internal
seal can be bad and oil from engine can leak in the distributor.
If so, hose it down with WD-40 to wash it out, wipe
out residue, assemble, and start car.
.

Next, check the air filter and housing and remove the
alum intake and closely inspect it for cracks. If that
hose has any cracks or the clamps are loose the vehicle
will run rough.

Please let me know what you find

Tim