I recommend "Race Against Time" by Kent Ertman from issue 81. This adventure is all about the skill challenges! And it has a real time limit on play--the PCs have three hours of session time to solve the riddles of where a number of "bombs" are hidden, minus the time it takes for their PCs to travel across the city. Somewhat reminiscent of finding the bombs in Die Hard III. I've run it in 3E and in 4E, and it works really well.
It has a prequel of sorts in issue 79 as the sidetrack adventure "The Best Laid Plans", also by Ertman (cartography by Chris Perkins), but this isn't essential, as long as the PCs have some sort of background knowledge or experience similar to that encounter. (If you read the "Race Against Time" adventure, you'll know what to do.)
The only potential drawback to the adventure is that you either have to use the city provided or you have to seriously adapt your own city or the adventure and its riddles. On the plus side, the adventure provides a nicely detailed city along with the adventure!