If the battery went dead again and required you to jump it again, I have to question two things, first the battery and second the alternator. First, the battery shouldn't have gone dead on one week, so that is my first guess. And yes, a weak battery could cause the RPM to change as mentioned.
In this case, I need you to have the computer scanned for codes. Since the lights have been on, the computer should have trouble codes stored. From them, we can focus on the problem at hand. Most nationally recognized parts stores will scan it for free. Also, while you are there, have them check the alternator and load test the battery. Again, most stores will do it for free.
Let me know what you find.
Monday, November 30th, 2009 AT 8:22 PM