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Did you replace either of the coils? Does the 1300 code still keep coming back? Do you have the DISTRIBUTOR at all or the 2 coil pack configuration?
A P 1300 code is extremely difficult to diagnose even for good technicians. You almost have to have an oscilloscope to check the trigger and feedback signals from pin number one and pin number two of the igniter to the engine control computer this code sets because the computer does not see an ignition confirmation from the. igniter. Is there any chance you have an oscilloscope or have access to one or someone that knows how to use one? Did you try another known good igniter? Are you 100% certain coil is strong and is snapping spark at least one quarter of an inch and is bright blue?
How the system works is the crankshaft position sensor and camshaft position sensor which are built into the distributor Send two waveforms to the engine control computer. It then calculates when it needs to send a trigger or IGT signal out to the igniter. The igniter then in turn grounds the negative side of the ignition coil for a predetermined amount of time then releases it which induces a secondary spark out of the ignition coil. When this happens the resulting feedback or magnetic field colapses around the coil sends a signal back to the igniter which in turn triggers a transistor that produces a square wave and sends it back to the engine control computer confirming that the secondary ignition took place for that cycle. The only way this code sets is if the feedback signal is not getting to the computer and a few rare cases I have seen where the trigger signal doesn't got sent out to the igniter due to possible wiring issues or pin fit issues and the computer doesn't see the obvious feedback signal because nothing triggered the igniter. With an oscilloscope you have a good ground then carefully back probe the IGT and IGF wires at the ignition coil to see if you're getting the patterns. Then check both wires at the computer and compare the signal wave forms. If there is high resistance either one of those wires or either one of those wires is even remotely shorted to ground it will kill the waveform. Because you monkeyed with the computer and replaced it it's possible you could have a loose pin fit at the connectors going to the computer. I would suspect that might be an issue. You need a pin fit gauge or an old computer that you can yank one of the pins out of and check your female pins in the connectors to make sure they're not loose. If you've already tried an igniter and you are 100% certain that you have a good ignition coil providing a good hot spark and field collapse then that only leaves a pin fit issue or wires between the igniter and the computer or the computer itself is failed again. I rarely see component failures a few igniters now and then but hardly ever a computer it usually wiring or pin fit issues. Click or copy the following link for additional information on how the system works.
You are welcome. Let me know how it goes.