97 Sierra 2500 Diesel 4x4. Key gets stuck in ignition at times. When it does, truck runs at 1/4 power, lights are dim, most everything electrical is not working properly. Have to play with ignition and key, finally get it out, restart truck and still only 1/4 power. This is happening quite often now. Took 1/2 hour to finally get the power up to full so I could drive the last time it did it. Do I need to replace the ignition? Do I have to pull the steering wheel to do so? What else could it be if not this? I'm stumped!
It definitely sounds like you need to replace at least the lock cylinder. See the image for the lock cylinder removal process.
As for the loss of power, I don't see how the lock cylinder problem can have an affect on it. Take it somewhere that will do a full scan for free, after you replace the lock cylinder. We'll go from there.