One problem related to gas recirculation valve (egr valve) has been reported for the 1999 Chrysler Concorde. The most recently reported issues are listed below.
Entering on-ramp to interstate. Car starts clunking, vibrating, clicking. Car dies on the on ramp on an interstate. Car died at 5:30 pm, it's dark out and almost hit by numerous cars speeding up to merge onto the interstate. 2 small children in the backseat. Cannot remove until help arrives because it is 5 degrees above zero outside. Towed car to local repair shop. Timing chain tensioner needed replacement. Clean sludge from oil pan. Found oil sludge and metal shavings in the oil pan and the oil screen. $834 in repairs and now engine has very loud knock. Repair shop tells me the engine is basically shot and nothing can be done to fix or salvage.