blazer skipping

[Kurt L]

i have a 2001 blazer with a 4.3 vortec 4 spd 5th gear over drive.i have replaced the distributer cap, rotor button,plugs.truck ran fine for quite awhile
then it started to skip evry now and then put it on the computer and said plug wire's were bad.so i replaced the wire's,ran fine for awhile now it's starting to skip again.[not all the time tho it's like intimite skip,some times it runs good with no problem then it skips again] mechanic that put it on computer says that it's a spark plug fouled out by the bad wires.can this happen?i'm old school not good with this new trucks.i've changed out the fuel filter also.it's driving me crazy this is wife's truck and our driver to take on road trips.hope to hear from some one that can help me with this.