I have a 1991 Cutlass Supreme with a 3.1 engine that is giving me fits. Idles rough, poor mileage, etc. I pulled trouble codes from it this last weekend, and got a 22, 23, 35, and 53. I 'm assuming that the 53 is the first code detected by the computer and that it (system over voltage) is the reason for the other codes being present.

Anyway, voltage at the battery with engine running was 14.3 volts. According to the Alldata flowchart, this means that the alternator is the problem. Is this true? Is there any way of verifying that this is causing the engine to run rough other than changing out the alternator?

 

As long as you have a good battery, unplug the alternator. That will drop the system voltage back down to 12.
What do the 22, 23, and 35 codes mean, I don't have a chart with me now.