My 88 na's been running insanely rich for over a year now, and it seems like it's been getting worse. Not just based on the overpowering smell of unburnt gas too, but from the 02 sensor voltage (usually runs at over 800mv at idle, should be under 100mv). The other day I had been doing some work to the UIM and forgot to plug the electrical connector on my BAC back in. It idled terribly, but no more gas smell. Sure enough, the O2 sensor reading was about 100mv at idle. A couple days of this and the same thing...if I plug the BAC back in, runs rich, otherwise runs great (but for bad idle).
Any ideas what could cause this? I don't mind a bad idle as much as I mind 12 miles to the gallon.

 

how do you mean it idles terribly, and in general does it idle higher or lower with bac unplugged?