Hello all!

So as the title suggests I have P0300 code (accompanied by some additional P030X codes)

I see a lot of posts regarding misfires, but none really address the issue directly or seem to have a good solution, so I figured I'd start a new thread and beg for everyone's input.

I don't just want to start throwing new parts/money at the problem, so I'm hoping someone reading this has had a similar issue, or understands the vehicles systems better than I do...

It first started a month ago, but I'd only get a misfire when I reached the top of the rev band (ie. near the redline), however now it happens all the time at any RPM and even at light throttle. If I cycle the ignition (even while still driving) the misfire goes away for a little bit, but always comes back after a short time, and it's happening more and more often.

I'm reluctant to think it's plugs or coil packs, I have a hard time believing multiple coil packs would fail all at once (car has 70,000 miles)... I also doubt it's the plugs since there are 2 per cylinder... but that's just my semi-educated guess. Maybe if the car detects a bad plug it shuts down the entire coil pack and/or injector???...But still, it would be weird to have no issues at all, and then have multiple random misfires all at the exact same time... You'd think with the relatively low miles you just get a single misfire if a coil started to go bad.... Which is why my gut tells me it's not plug or coil related.

My hunch is it's fuel pressure related?? Does anyone know if the Merc engine shuts off the injectors to random cylinders if it detects low fuel pressure?

I know it could also be a vacuum leak, blocked fuel filter, dieing fuel pump, or even a control module issue... But does anyone have a good idea about what's most likely the cause?

Thank you in advance for any help.