car has lost power
 

I have a 91 gxl,the car was running fine and when I got to a stop light the car started ideling verry low,I checked the haynes manual and pulled the codes and got number 17,I checked everything acording to the manual and everything was in specs,can anyone help?

Code 17 is the 02 sensor, which would mean the ECU is less able to adjust the mixture at idle. Check the 02 sensor wire to be sure it hasn't been disconnected.

When you say it's "lost power", does that mean the car drives sluggishly, or just that the idle speed has dropped?

the idle speed has dropped and when you give the car gas it takes forever to get to speed,now also when I checked the codes again it's also giving me a code 3,I bought a new O2 sesor,but now i'm trying to figure out the code 3, thanks for the reply.

Code 3 is the crank angle sensor, which would definitely affect power. I think the ECU uses static fuel and timing tables (limp mode), if the CAS signal isn't being received. Much like when the OMP fails.

Code details here: http://www.rx7city.com/ecucodes.htm

I'm wondering if my harness is bad,I checked the cas and the coils like the hayne manual aclled for,everything is within specs,I even swaped out computers and cas and still the same thing,if its in limp mode is there any way to get it out of limp mode?

Did you test the CAS and coils at the ECU or at under the hood? If you haven't already tested the CAS G-signal at the ECU, pins 3G & 3H should have less than 1.0V under all conditions. This is page F1-80 from the S5 FSM:
http://members.cox.net/linspace/CAS.JPG

And short of correcting the problem or replacing the ECU with an aftermarket upgrade, there's no other way to get out of limp mode.

I only cheked under the hood,I'll check under the dash,the computer that I swaped with was a upgrade from superchips,and it still did the same thing.