It is a well-known custom among many Muslims to avoid pork their diet:
16:115 He has only forbidden you dead meat, and blood, and the flesh of swine, and any (food) over which the name of other than Allah has been invoked. . .
Here's a small history of the Qur'an: It was revealed to the prophet Mohammed over more than 20 years. Qur'an was not written down on paper until years after Mohammed's death. The surahs were memorized by companions of Mohammed, then written down later when the companions were noticing other people taking these surahs and putting their own little twist on them, to put the words of the Qur'an in line with their own beliefs.
Because the Qur'an was revealed at the time it was, it addresses many things that were current issues of the time. It states that each prophet before was addressing the times and people of that period. Of course, each message had many obvious parts that carry over to the current times.
Now, why do you think pork is forbidden in the Qur'an? Could it be one of those things that is addressing the specific times when the Qur'an was revealed? One reason people tend to say that pork is forbidden is because it is dirty. The pig in the slaughterhouse is fed and treated the SAME way the cows and chickens and turkeys and lambs are treated: POORLY. They are fed the SAME type of food and given the same type of living arrangement.
There is no legitimate reason that one should avoid pork if they do not avoid beef and every other animal. In Mohammed's times, there was not a safe way to prepare pork, AND pork was not a type of animal that was easy to raise in a desert climate. It was incredibly inconvenient, therefore pork was not something the people of that area ate.
Yes, the Qur'an says to avoid pork, but then again, the Qur'an was revealed to a specific peoples in a specific location at a specific time. And again, as we know, different prophets brought specific messages and miracles (from Allah) to specific times and people.
We MUST remember this. If you are a Muslim who avoids pork, but feels comfortable eating beef and chicken, then maybe you should reevaluate this. Ask why! Never just take something that doesn't make sense and accept it blindly.