So I've searched the hell out of the forum, and used Google's "site:" search feature, but really haven't found an exact match to my symptom. I've got quite a few little things bothering me about my car at the moment, but the one I'm most concerned about is currently coming from my oil filler neck. Through a rather stupid and mindless mistake, I left my oil cap off one day a few weeks ago, and then when taking a turn a bit quick, lost the cap. So I've been without cap for a couple weeks (don't ask), and finally got one day before yesterday, but I've finally managed to nail down a symptom I was having from before but could never figure out.

I had noticed that from time to time after shutting down (unknown precursory acts), my engine bay would smell strongly of... Burning? Basically hot exhaust, but with a twinge of something else that I really can't seem to identify. Anyway, after getting home from work this morning, I popped the hood, and noticed by chance a small stream of smoke exiting my newly replaced oil cap. I opened the cap, to see if I could figure out what the hell, and found my entire neck filled with smoke, of a... what I think to be grey nature. It also seemed to wreak of gas at first. The gasoline smell quickly dissipated with a quick puff into the filler neck, but the smoke returned, and was quickly found to be coming from the purge valve entrance.

I've read the factory service manual, and will conduct a test soon, but I wanted to get some preliminary opinions here. If it helps, other potentially related symptoms include a quick puff out the exhaust at start up, and I think a minor vacuum leak somewhere (my idle wanders between 760, give or take 25). My MPG is about 15-16 under my driving (consistently 3800 and above, cruise at 90-110), and if I had to guess... 18-20 at "normal" speeds. I know my TPS has a dead spot at... ~30% throttle, but my tip in is great, and my decel is seemingly spot on, or damn near. ACV's work. I do consistent oil changes every 2500-3k, have no fuel leaks (but am always below 1/3 tank, yes... I know), and am adamant about everything functioning properly. Oh... one more thing that may be related... upon coming to a stop, and getting out of gear, it'll stumble to... 550? Then come back up on me. I know it's a vacuum issue, as braking affects it quite strongly... I'm guessing this might be a pretty obvious one now, but... yeah.

Sorry it's so long. But I dig on the details. Ideas?

 

Purge control valve operating properly?