Chevrolet: 2001 Tahoe rough idle, plug wires, heat shield

Question
My 01 Tahoe has 107,000 miles on it.  I need to do the 100K tune up and wanted to change the plugs myself. I still find it hard to beleive that I shouldn't change the plugs for 100K... The plug wires have metal casement at the block, which I suspect is just a heat shield.  I have tugged on these wires harder than I thought I should have to to get them off, but before I tug much harder, I wanted to confirm that these plug wires should just pull off like old plug wires use to.  Also, I was going to clean the throttle body as I am getting a little rough idle especially when the condenser cycles on and off. , any suggestions on what works the best on cleaning the throttle body?  

Answer
Walt ;
Hi ,look to see if the shields are bolted on , try to twist the wires off,they should not be that hard - at that many miles you should replace the wires any way.  Its wild that plugs can last so long now a days. I can remember changing them  often in the oldercars.