I was browsing the used book store the other day and came across this book and the summary on the back of the book seemed wild, but I set it back on the shelf and walked out of the store. After not being able to stop thinking about it all weekend I went back, but I couldn't find the book at all. And searching the internet hasn't been very useful, it just pulls up non-fiction books about mummies or about banditos, but not a novel about both.
From what I remember from the back cover the main character is an Indiana Jones type character that discovers a tomb in Egypt with a fancy sarcophagus and several smaller coffins with mummies. He ships them back to LA to study them and along the way they get stolen by Mexican "banditos". Then he has to rescue them. The end of the summary heavily implied there was something mystical at play, but never said what it was. But I thought it was about the mummies coming to life.
If I remember which corner of the store I was in (a good assumption) and if the book was on the correct shelf (also a reasonable assumption), the author's last name probably started with a W. I remember the cover as being overall yellow with the face of the Indiana Jones character prominently featured, fedora and everything. It also showcased the sarcophagi and I'm pretty sure there was the typical beautiful woman / love interest. The cover art was a painting that made me think '90s, but that could be way off.