I did my 280 1995 this weekend,had a misfire which would go away with a restart, After being assured that it was the coil boots or the engine harness,it turned out to be a coil so i changed all three. With my discount at the local dealer they were $55.00@.
The primary resistance both new and old was 0.9-1.00 ohm on a dvm was not able to get a reading on the secondary sides.
Check your coils before spending a lot more money. The coil boots and wires should have a 2000k ohms resistance,check those also and replace if insulation is broken or show signs of arcing.
Let me know of your success.