Sorry for the long delay, I haven't had any real time to peek under the hood until a few days ago. Anyway, here's what I did, in order of the advice I got.
I don't know when the last FULL MECHANICAL tune-up happened, i've only owned my 200 for about 5,000 miles. In that time, I've done all the general upkeep as well as replaced the clutch, tuned the brakes. That includes fluids, some replacement parts, cleaning stuff like the MAF, valves, etc and general things like that. I popped the distributor and didn't notice anything suspicious, however one of the distributor cables wasn't seated well in the terminal. So when I reassembled, i got it all the way in and made sure it was seated properly.
concerning a fuel pressure leakdown test, i didn't have enough time under the hood to research what that means or how to do it, but i'll try that when i get the chance.
when inspecting the IACV, i noticed that the inlet from the intake to the hose that runs to the IACV is much smaller then the stock one. This is because i installed a short ram intake and the aluminum pipe it comes with has a smaller inlet for that section of hose. I guess this means there is restricted airflow to the IACV, so could that possibly be the problem? I'm not familiar with how much air an IACV needs, but it might have something to do with it.
finally, with regard to the radiator coolant levels, everything checks out as normal. however, on a sidenote, a few months ago my 200 spat out a "low coolant level" code, even though I checked and everything was normal. I cleared the code and dismissed it as an electrical problem because i had just replaced the clutch so i suspected I might have done something to trip a sensor somewhere.
So far, no other codes, aside from a pesky O2 sensor which comes on and off every once in a while. Seems to be faulty wire...
The good news however, is that I haven't had any problems since I fixed that distributor cable. Maybe that actually fixed it? I honestly don't know. I'll try to be more consistent with getting on here so I can TRULY get this fixed :-)