ZL1power69

hi,im hoping you can help me with another little problem on my 2001 blazer,i started hearing a noise under the hood,i found it but im not sure why,its coming from the distributor cap,when i lightly push down on the top of the cap the noise stops,when its idling it doesnt seem to make the noise but when you give it a little gas it starts, do you have any ideas??? by the way the rear window & hatch are working fine, my email is dougbrissey@suddenlink.net 304 629 8123, thanks alot, doug