i was driving my car and all of the sudden it had just lost power. I put the throttle down to the floor and the tach stopped at 3500 and it wouldn't shift either. Once I got home I checked the codes and I got code 15. I have had similar experiences, one was a O2 sensor, and I replaced it and it drove fine.
Just started it up and the idle went to 2300 and them dropped back down to 700. It also started to backfire. When I revved it up, it would take a second to rev, the it would go.

 

Since you have a code 15 wouldn't you troubleshoot that code? Coolant sensor issue. http://www.chevythunder.com/cts_diagnostic_pg2.htm

 

I've got a code 15 right now (86 IROC 305 TPI) and it runs like a scalded dog anway. No issues spinning tires, getting pushed back in the seat, hauling *** down the highway, etc.

I'm about to go out and check the voltage on the yellow wire now as a second step (replaced the sensor and plug yesterday). Getting to the computer to check the wire from the sensor/plug back to the computer will be a little tougher (for me).

I was looking for the info on the computers (in case I have to buy another one) when I ran across this thread.