So, today I swapped out the coolant temp sensor because it was a cheap part not really worth my time to test the old one. Checked continuity in the harness. Seemed fine. Took it for a spin and it did the same old dance. Limped it home. No new codes. Went for a ski while it cooled down, went back to start it again and it ran like crap. Started rough, low idle, jumpy tach. It seems like it may be getting progressively worse all around.
Next I'm going to test the O2 sensor. Up here at 10,000 feet we only get a couple good hours per day to work outside before the temp drops, so I basically get one thing tested per day. Kind of frustrating.
Can anybody tell me which harness on the passenger fender is the one for the O2 sensor?
Also, digging out my infrared thermometer to test the cat tomorrow. I would agree with slartibartfast that it didn't seem like a cat problem but its a pretty quick test so i'll check it anyway.
Thanks for your comments everybody!