07-4dr Code P0505 and exhaust leak in engine bay - goes into cabin and engine stutter

[Lafiro]

To get right to the point, over the last year, I have noticed that both the engine sounds like air coming out during any acceleration loudly and that while idle, if the air is not set to circulate cabin only, it pulls in exhaust. I had a mechanic tighten the bolts but this seems to not have helped much. I really don't know what parts may need to be changed. Suggestions?

Now, I am also seeing P0505 errors. A few times with maybe the AC on or rear defrost, when the car is stopped and in gear, it will stutter and almost shut off. This will instantly throw the check engine light. After reading and searching here, I have purchased 4 things, air filter, throttle body cleaner, MAF sensor cleaner and sea foam engine motor treatment.
Any suggestions on how and where to apply the sea foam stuff and if what I purchased above would help resolve the low RPM and engine stuttering?

Thanks!
PS - Attached is a short log of whats happening with some output from the car. There are many more sensors but I don't know if this helps anyone here identify any other problems. Towards the end, the car almost shut off a few times for around 10 seconds.