One problem related to coolant leaking has been reported for the 1999 Honda Passport. The most recently reported issues are listed below.
The engine coughed and choked, and the vehicle stalled. I at first thought it wasn't warmed up enough before I started driving it, so I warmed it up in the morning for about 5 min. The problem didn't occur for a short while, then came back. I brought it to a Honda dealership. They tested it and advised me that the head cylinder gasket was blown, causing coolant to leak into the combustion chamber. Also one cylinder head is cracked and had to be replaced. The other cylinder head had to be machined. It took about a month to get it fixed. I found it very unusual that a major engine work had to be done with less than 60,000 miles.