There is also an ignition control modulke in the circuit that controls the coil firing, I think they are calling it a power transister. That would have been my first choice if it weren't for the code your getting from the computer but that could be old of misleading. Here's some diagnostic procedures that may help you. They say for up to 86 but I checked the schematic for the 87 and they are identical. The stuff in the beginning is basics you may already have done.

In case yopu need the schematic, I'll include it at the end.

1981-86 Vehicles

BATTERY VOLTAGE (NO LOAD)

With the ignition key in the OFF position, connect a voltmeter to the positive and negative terminals of the battery. The reading should not be below 11.5 volts. A lower reading indicates a faulty battery, charging or starting system.

BATTERY CRANKING VOLTAGE

1. Connect a voltmeter to the battery and set to the appropriate scale.

2. Remove the coil wire from the distributor cap and ground it.

3. Crank the engine for approximately 15 seconds. The voltage reading should not be less than 9.6 volts while cranking. A lower reading indicates a faulty battery, charging or starting system.

SECONDARY WIRING TEST

With the distributor cap removed, connect an ohmmeter to each end of the spark plug cables. The resistance readings should be less than 30,000ù. If the resistance readings are greater than 30,000ù, replace the distributor cap and/or plug wires.

IGNITION COIL SECONDARY CIRCUIT

With the ignition key in the OFF position, and the coil wire removed from the coil, connect an ohmmeter with one probe to the coil wire socket and the other to the negative terminal. Check both coils. The resistance reading should be between 7,000-11,000ù. If not, replace the ignition coil.

POWER SUPPLY CIRCUIT

1. Connect a voltmeter with the positive probe to the B terminal (power source) and the negative probe to the distributor housing.

2. Turn the ignition key to the ON position.

3. The reading should be between 11.5-12.5 volts. If below 11.5 volts, check the wiring between the ignition switch and the I.C. unit.

POWER SUPPLY CIRCUIT (CRANKING)

1. Connect a voltmeter as in Step 1 above.

2. Pull the coil wire from the distributor cap and ground it.

3. Turn the key to the START position and observe the voltmeter while the engine is cranking.

4. If the voltage reading is more than 1 volt below battery cranking voltage and/or is below 8.6 volts, check the ignition switch and wiring from the switch to the I.C. unit.

IGNITION PRIMARY CIRCUIT

1. Connect a voltmeter negative probe to the I terminal and the negative voltmeter probe to the distributor housing.

2. Turn the ignition key to the ON position. If the reading is between 11.5-12.5 volts proceed to Step 3. If the reading is below 11.5 volts proceed to the Ignition Coil Primary Circuit test.

3. Connect the voltmeter positive probe to the E terminal and the negative voltmeter probe the distributor housing.

4. Turn the ignition key to the ON position. If the reading is between 11.5-12.5 volts proceed to the I.C. Unit Ground Circuit test. If the reading is below 11.5 volts proceed to the Ignition Coil Primary Circuit test.

IGNITION COIL PRIMARY CIRCUIT

1. Place the ignition key in the OFF position.

2. Remove the coil wire from the coil.

3. Measure the resistance between the two terminals of the coil. The resistance should be between 1.04-1.27ù. If not the ignition coil is defective and should be replaced.

I.C. UNIT GROUND CIRCUIT

1. Connect the positive probe of a voltmeter to the housing of the distributor.

2. Connect the negative probe of a voltmeter to the negative terminal of the battery.

3. Pull out the coil wire from the distributor cap and ground it.

4. Turn the key to the START position and observe the voltmeter while cranking.

5. If the voltmeter reading is 0.05 volts or less, replace the IC ignition unit assembly.

6. If the voltmeter reading is more than 0.5 volts, check the distributor ground, wiring from the chassis ground to the battery including battery cable connections.