Mitsubishi Repair Problems? Ask a Mechanic for Answers ASAP
Hi,Its possible there are a few things going on here given your order of events.With regard to the coil... these are sort of common to fail as they get older, and particularly aftermarket coils are famous for failure even within a year or months (so genuine is the only way to go here).
So for starters in that regard we would want to at least start by pulling the intake and swapping the #5 coil to the front side (for easier access) as well as the spark plug to see if the problem changes cylinders.Before that though, the no start is a concern of course, since we won't be able to get a misfire fault again if the engine won't run.
When you crank the engine does it sound normal or does it spin faster/slower than you are used to?
If you apply the gas pedal while cranking will it start?
With regard to the coils.... it is not a bad idea, however it can be pricey as they are around $100 each last I checked. While you can get aftermarket ones for less we have had absolutely horrible experiences with them and you really need to stick with genuine coils/electronics on this car.
Before getting into any of that though, let them find out what the cause of the no start is... investing that sort of money in the coils before knowing what is going on with the no start will be counter productive, and as well there is always the chance that the cause for the no start may have created the misfire to begin with.When they check it out I would definitely start by making sure the timing belt is intact... they can do that by watching in the oil fill hole while a helper cranks the engine to make sure the top of the engine is moving etc. While it won't tell if the belt slipped, it will tell if it broke/stripped which is more common anyway. If the top end is moving inside then they will want to proceed with normal diagnosis (check for spark, fuel pressure, etc).
Once the problem with the no start is found, if it is seemingly unrelated we can pursue the misfire issue... however there are decent odds that there is a relationship there. If the timing belt slipped before stripped for example it will misfire before total no start. Same for a bad MAF sensor, a tank of bad gas, and so on... lots of reasons for a no start could be at fault for the misfire too. If the misfire is still present after the no-start condition is resolved, then we would want to proceed as I mentioned before, moving the #5 coil to one of the front cylinders and the #5 plug to a different front cylinder, then if/when the misfire changes cylinders the new location will tell you which part was at fault and so forth.