Not sure about all your issues but get the bosch plugs out of there. They're crap for our cars, you want to use motorcraft or autolite double platinums. I think the pcv valve could help you out a good bit if it's clogged. And with OBD1 you can do your own self test, don't ask me how though, but I know it involves a paper clip and watching how many times the CEL light blinks.
