Did you replace the plug wires? You could test your coil with a new wire. Try this:
(1) To set up the test, remove one spark plug wire from its plug, then remove the spark plug using a spark plug socket. Next put the spark plug back into the spark plug wire. Be careful not to let anything drop into the empty spark plug hole -- very bad. Holding the plug wire with insulated pliers, find a spot on the engine that is a good and easily accessible grounding point. Pretty much any exposed metal, including the engine itself, will do.
Holding the spark plug wire with your pliers, touch the threaded portion of the spark plug to the grounding point. Have somebody crank the engine with the key, and look for a bright blue spark to jump across the spark plug gap. If you see a nice, bright spark (clearly visible in daylight) your coil is doing its job.
(2) Using a multimeter: Find the resistance specifications for your car's primary coil winding in your repair manual. Then using a multimeter, place the leads on the smaller, outside poles if you have a traditional round coil, or on the indicated poles if you have a newer enclosed unit. If the reading is within the range indicated in your manual, your primary winding is ok and you can go on to the secondary test. if it is even a little out of spec, the coil should be replaced.
The secondary winding of your ignition coil delivers the spark to the distributor to be sent to the spark plugs. If it's bad, you'll get a weak spark or no spark at all.
To test the coil's secondary winding, attach the test probes to the outer 12V pole and the center pole (where the main wire goes to the distributor). Determine the resistance and check to see if it's within the range indicated in your repair manual. If it is, your coil is up to the task. If it's even slightly out of range, your coil should be replaced.
Good Luck Let us know how you make out.