2000 Dodge Intrepid Cylinder Misfire help
So this has been the forum I've come to for troubleshooting in the past, and everyone here has been a huge help, so I figured I would make a post looking for a little help with the problem that I am having now
For the past couple months, my car runs fine city. I don't notice any huge issues with it other than the fact that it idles at ~600RPM which I think is a little low. But no CLEAR issues. However, every single time I take the car out on the highway, the engine light randomly blinks for random periods of time. There does not appear to be any connection between what is going on and when it blinks as it appears to be totally random, and it won't even complete a full blinking cycle. It will blink 5 times, 1 times, 1.5 times, 3 times, 6 times, etc. and then totally go out for a random period of time before blinking again.
Once in a blue moon, it would remain solid after blinking, and gave me a chance to run the code. The built-in code-running cycle in the car gave me P1684 (battery has been disconnected within last 50 engine starts) and P0300 (multiple cylinder misfire). The engine does not appear to be misfiring, but at the same time I cant honestly say I know what that would feel like. I have taken the car to a private shop and they couldn't find anything wrong with it.
I have personally replaced all 6 coils and all 6 plugs and the issue remains.
More recently, this issue has been showing up during city driving too so I took the car to advanced auto parts to run it with a real code reader. The code reader now gives me the following: P0303 (cylinder 3 misfire), P0306 (cylinder 6) and P0300 (multiple).
I plan on driving for a bit and testing it again to see if 3 and 6 remain the culprit or if the misfire truly is random but like I said, the general fix I've found is either plugs or coils and that didnt help.
Can anyone give me an idea to move forward with if someone is particularly familiar with this issue?
Thanks so much for any help you can offer.