Thriller, scene were someone is dissolved in acid in motel

Hello!

A book I read when I was 13 or so in 2000-2002. Cover was a silhouetted man running through a tunnel or sewage tunnel? Super trashy book, could have been Lee child? Very descriptive about guns and thought process. The only scene I remember is a dead body being dissolved in acid in a bathroom of a motel or something like that.