Popping in Exhaust

[lukecp]

While my truck is running, from 1000-3000 RPM, i hear a small "pop" coming out the exhaust. It souds pretty normarl, just vroooooooom-pop-vrooooooooom. It has done this before, but giving it a tune up stopped the noise. I gave it a tuneup about 3,000 miles ago, and now its doing it again. I posted about this before, and someone said to check for an exhaust leak. I can't find one anywhere, and i have replaced both the flange and collector gaskets on my headers. The distribuotr cap and rotor are both fine (i inspected them yesterday), and the plug wires look fine. I use Accell Super Stock plug wires on the truck. I had problems with one wire touching the headers, getting burned and making it miss. I just replaced the wire, and that wasn't the problem. I'm going nuts tring to figure this out. I'm thinking that maybe it is the plug wires. Any ideas on what would cause this?