You stated above that files have anywhere from 3 to 50 fields, but you weren't clear on whether a single file would have the same number of fields in each line...
Therefore, my answer makes the assumption that a file has the same number of fields for each line (though different files may have different numbers of fields). If that is not the case, please ignore the rest of the response.

You can try and split the first 5 lines of a given file on each of the different known deliminators. For each deliminator tested, if the 5 lines you test return the same length array (greater than 1, as that is the default case if there was nothing to split on), then that deliminator is likely to be the correct one.

While this isn't 100% guaranteeed, many of the files should process correctly this way, and then you may only have a few files to work by hand after verifying yourself what the true deliminator is.