Audio sync problem on some files after conversion

[rubiohiguey]

There are some Ripped video files that I try to convert (into h264) and adjust audio volume. Problem is the "original ripped" file (divx in avi container, mp3 audio) plays fine but when converted, there is audio sync problem. Ffmpeg indicates some header problem. I tried even extracting audio via Adobe Audition and other software and it still does not work. When I open this "original ripped" file in Premiere Pro, it has audio sync issues as well. Media player classic or mediabox (WD TV) plays the file fine, but as soon as I try to "edit", audio sync issues arise.

Also tried both vcodec and acodec conversion in ffmpeg, tried various video conversion software, etc., to no avail, anything but the "original ripped" file has audio sync issues.

When I use Audition to extract audio, if I extract it as mp3, it is up to 15-20 seconds shorter file. If I extract it as wav, it is the same length as original video file, but pegging it with video causes audio sync issues as well.

Also tried Avidemux, Video copy and Audio with filter for gain, saving as avi with mp3 audio ... same problem, audio sync is lost.

Ffmpeg shows me this error:
Stream mapping:
Stream #0:1 -> #0:0 (mp3 (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
[mp3 @ 0000000000362aa0] Header missing
Error while decoding stream #0:1: Invalid data found when processing input

I assume it is some timecode matter, but I have so far not been able to resolve it. Would anybody know what to do with this video?