2001 Chevy Impala 2001 Impala Follow up on memory scan code

2001 Chevy Impala 6 cyl Automatic 105000 miles

Hi. I don't know the protocol here and don't know if you got my response on original post. I'm having trouble with the check engine light being on. As advised, I went to Auto Zone and had the memory scanned. It came up as "Cylinder 1 misfire". The guys at Auto Zone said it was either the spark plugs or the spark plug wires. Here's the deal. I had a tune up on this car with plugs and wires replaced in July 2008. I did notice that the plug cap marked 1 comes off a lot easier than the other ones do. Is this a bad connection or something? Also, the odometer light comes on and off when I wiggle the trip odometer knob. It will not stay on for any length of time and what time it is on, it is dim. Does this indicate a short? Please let me know as soon as you get a chance and thank you very much for your help and advice.