Did you disconnect the spout connector at the distributor?
If you did not, then this is normal as the ECM is controlling the timing and it will vary.
If it is disconnected and is varying, it could be the distributor or the timing chain that has too much slack.
Place transmission in NEUTRAL or PARK with Air Conditioner Heater in OFF position.
Cylinder Numbering And Distributor Location
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Connect an inductive timing light.
Disconnect the single wire in-line Spark Output (SPOUT) connector or remove the shorting bar from the double wire SPOUT connector located near distributor.
Start engine and allow to reach operating temperature.
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With engine at timing rpm, check or adjust initial timing to specification. See: Ignition Timing Specifications
Reconnect single wire in-line Spout connector or reconnect shorting bar.
Check timing advance to verify distributor is advancing beyond the initial setting. If it does not, perform EEC IV Quick Test. See: Computers and Control Systems Reading and Clearing Diagnostic Trouble Codes
Remove test instruments.
Images (Click to enlarge)
Wednesday, February 5th, 2020 AT 4:10 AM