Q: Electricity gauge reading low voltage. Just charged my battery and replaced alternator in April. Connections look good.

I have been struggling with rough idling, misfiring, and low voltage for the past week and a half in my 1998 Jeep Grand Cherokee Laredo. It started out misfiring and voltage dropping, and the check engine light came on, so I borrowed a friend's code reader and it said faulty crank position sensor, bad connections, and check charging system. I checked my crank position sensor, and it was covered in oil, so I cleaned it off, and it hasn't been misfiring quite as bad. I changed my spark plugs, distributor cap and rotor, had my battery charged overnight at Advance Auto, and tested the next day and they said it was fine. I took my battery home and put it in my car and immediately my voltage gauge read only about 11 amps. I don't think it's the alternator, because i replaced it in April, and the battery read low as soon as I put it in my car, indicating what I think would either be a connection problem or a battery problem, but not a charging problem. im stumped and very frustrated.