1989 300E starting problem

I posted a thread this morning on how to remove the alternator and the starter but before I do so I would like to make sure that these could be the problem.

My 1989 300E had a hard time starting a week ago. When I turn on the key the lights came on, the radio worked, the A/C worked, etc... but the car would not start, not even a cranking sound. I tested the battery and the voltage was 12.57 volts. I then jump started it with my other car and the 300E started no problem. I tested the battery when the car was started and the voltage was at 14.0 volts. I assumed that the alternator was charging the battery. I started it again about 6 or seven times with in 3 days and there was no problem.

Yesturday I tried starting my car and it did not start. Same as before. I turned off the A/C, radio and lights and tried to start it again. It took a few seconds but then the car started without a boost. Now everytime I start the car I make sure that the A/C, radio and lights are off.

I took the car for a drive around town for about 20 min and stopped at a coffee shop for about 10 min but I left the car running. When I returned to the car my ABS warning light came on and my warning light for an exterior light burnt out was also on. The car was also running a little rough. When I turned the radio and A/C off the car ran excellent and the warning lights turned off. When I put the A/C back on the car ran rough and the warning lights came on again so I turned the A/C off again. When I arrived home I turned the car off again making sure that the lights, A/C and the radio were off. Then I tried to start the car right after again and the car did not start, not even a sound yet the lights and radio worked. Today I jump started the car, put the A/C, radio and lights on; the car started no problem and there were no warning lights. I took the car for a 5 min drive and still not warning light.

I assume that the alternator and or starter need replacing. About 6 months ago I changed the voltage regulator on the alternator, Could this be the problem also?

I am sorry that this thread is so long but I wanted to make sure that I got everything in there.

Please help!!!

Fab