Mitsubishi Repair Problems? Ask a Mechanic for Answers ASAP
Sometimes what will happen is when you have oil on the plug wires it will damage the rubber on the spark plug boot. Once it's disturbed, the spark will arc through the boot and into the cylinder head instead of the spark plug. Spark will follow the path of least resistance. Remove the wires one at a time and look for any sign of arcing or burning on the boot. If you see it, then you will have to replace the wires to resolve the issue.
It is also possible but unlikely that you have the firing order wrong if you took them all off at the same time.
Please let me know what more I can do to assist you today. Also, please remember to rate my answer, Just Answer does not compensate me for my time and resources. Follow up questions are included in the price of your question. If you are using the free trial, or have a subscription a rating is still required.Thank you so much!