I'm assuming you have a 3.5L engine versus the 3800 since you can't find the spark plugs.
Here are a few helpful links:
http://www.automotiveforums.com/vbul...spark+plug+3.5
http://www.automotiveforums.com/vbul...ght=spark+plug
Spark plugs are a good starting for random or specific misfire DTC error codes.