"Indiana Jones and the Army of the Dead" by Steve Perry - I finally got through reading this earlier this year.
And I've read all the American-released original Indiana Jones novels (the ones by Rob MacGregor, Martin Caidin and Max McCoy) - I've also read all of the original "Young Indiana Jones" books. Oh- and the two young adult original Indiana Jones novels that were released shortly after KOTC released- "Indiana Jones and the Pyramid of the Sorcerer" and "Indiana Jones and the Mystery of Mount Sinai".
It might be fun to go back and reread these at some point- particularly with the "Young Indy" books- it'd be cool to read these in chronological order, as the publication order is definitely not in chronological order.
Oh yeah- and I still want to read those Wolfgang Hohlbein novels- but I don't know enough German to read them in the original language. But I am so grateful for the fans here who have offered English translations- those are very cool! I hope to delve into those when I have the chance.