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The next item to look into here will be the Fuel Injector for cylinder #1. With the engine running, unplug the electrical connector to the injector. The engine should respond with the worse idle. If not, the power to the injector should be tested. You can do this with the use of a noid light. If thenoid light blinks, the injector will need to be replaced. If the injector tests good, then you will need to test for intake air leaks around cylinder #1 and then ultimately, a compression test. If the Lucas additive helped a little, sounds like the injector may be partially clogged and will need to be replaced. If my answer has helped you, please help me by leaving a rating or accepting my answer so I may be credited. Rating or accepting my answer does not cost you extra. It allows me to be credited for my work. Please rate or accept. You can ask follow-up questions after you rate or accept.