I think I managed to solve part of the problem.
1 – I installed Premiere Pro CS6 to test if it solves the problem.
2 – After many tests, I tested the encoders:
“PPCS6 H.264”, “x264pro” and “MainConcept TotalCode”.
And one of the tests I got a result:
With the encoder default Premiere Pro CS6:
The result was slightly better than in CS5.5, but continued with high peaks in bitrate.
With MainConcept TotalCode:
I changed the buffer to minimum values ​​Bitrate: 209984bytes (as the picture shows). The standard was around 3009984bytes (3x more) …
And the bitrate was very stable.

I googled a bit and found that the bitrate buffer is used in streaming video.
I liked to have found a “solution”, but what I realized when comparing the saved videos was this:
– Making encode with the default preset of Premire Pro, the video has more peaks because there is no way to control the bitrate buffer. But the video images are sharper.
– In MainConcept TotalCode I managed to get the stable bitrate, but gets a little blurry. (I could not find a solution yet for the blurry). (The difference is little, but large TVs may give notice to).
– In x264pro the results were close to the preset default Premiere Pro.
For those who want to have more control in the videos in H.264, use the MainConcept TotalCode, with it you will have more control, but maybe not 100% of the control you want. But it is better at various points in comparison with the standard H.264 encoder Premiere Pro.
Richard Herd, thank you for helping me. All data you posted helped me a lot, so did I seek the real problem.
I do not know if the problem is the bitrate buffer, but changing it, did normalize bitrate.
Thanks a lot again. 🙂
I will try to see if I can control the “bitrate buffer” in the Premiere Pro encoder, or if I can do the videos on MainConcept TotalCode be sharper.