[Bahlzeron]

Thanks for the reply ion,

Checking and cleaning all connections was the first thing I did, months ago, and have repeated thrice, to no avail... in fact everything has been tried multiple times (by me and a garage) all with the same results. With the oxygen sensor unplugged it runs fine.. a little rich, but otherwise fine. When I plug it back in, random misfires, stumbling, and stalls... if I keep the throttle cracked to keep it running, when I let out the clutch it falls flat on it's face, as if the mixture is crazy lean. Unfortunately I don't know anybody that has HP Tuners... in fact I don't know anybody that's into cars.. or motorcycles really. Both communities around here are pretty stuck up, if you weren't born into it, you don't belong.

And as far as the length of drives I went on to test.. they were much longer than just a few miles, the mileage I listed was how far they got before failure. The garage I brought it to confirmed bad oxygen sensors. I need to find what is killing them.

And yes today I put 90 miles on it with O2 unplugged, ran fine...mostly, slightly rich (expected with sensor unplugged). engine light came on finally after I got back and car was sitting idling for about twenty minutes (why didn't it come on before with any of my other extended test drives?). When I plugged the sensor back in it went right back to being a (insert vulgar expletive here)

A thought I thunked...would the downstream O2 sensor cause this? I've been told no.. but, maybe?
Another thought I thunked.... combination of bad downstream and bad catalytic, or just bad cat?