2001 blazer noise under distributor cap

i have a little noise that ive found is coming from under the cap,when i push gently down on top of the distributor cap the noise stops, there is no noise when idling but give it a little gas and it starts,my email is dougbrissey@suddenlink.net, thanks, doug

Make sure the distributor cap is secured tightly to the distributor, it shouldn't move. The bushings in the distributor may be worn allowing the shaft to wobble as it rotates causing the rotor to contact the cap.