if you developed a miss in a 1988 2.8 multiport V-6 hiow would you go about isolating the cause?

Answer 1

Sounds like an electrical problem.
If the engine hasn't had a tune up in the last 15K complete first, including the cap & rotor. Set timing to manufacturer's specifications. If problem persists.
Inspect the pickup coil for corrosion.
Check your spark plug wires with an inductive timing light.
Replace any defective wires, if problem continues replace the plug.
If electrical checks OK then there may be a fuel delivery problem. For MPFI remove the coil wire & crank the engine for 10 seconds. Remove all spark plugs. If you incur a dry plug then the injector is malfunctioning.

Good Luck. . .

Answer 2

the cause is not the biggest concern in a vehical that old i'd just get her fixed chulk it up as where and tear