I have a 93 Z71, I have a remanufactured 350 with about 6k on it.  Last winter something happened, dont know what and it started running like a couple plug wires fell off.  My plugs wires, cap and rotor have 6k on them, I replaced my fuel pump, filter, and rebuilt my throttle body with a new gasket kit, and clean injector screens.  My truck will run good for a day and then just starts missing like crazy and stalling and then it clears out and is good for a day or so.  I have replaced all kinds of stuff, I am going nuts on this one.  I even tried another computer but with the same prom chip.  Anyone have a fantastic suggestion?  Thanks.  

your plug wires are new as you say..but have you made sure they dont touch anything like the exhaust? if they burn through and get exposed they will make your engine run like *** as you can imagine, but it will go away here and there   depending on if it makes contact with metal or not..basically I'd check the wires and make sure they are tight and as short as you can possibly make them between your distributer and plug, so that there is no chance of them rubbing on anything ie: exhaust manifold.  

I saw no spots where the wires were touching manifolds or arching, I replaced them last night with a known good set off my suburban, no change.  Thanks for  the thought though.  I am considering my ignition module, i put another old one on that worked good when it was removed, no change.  Not sure if those go bad from sitting around a while?  

Have you checked the cam to see if it has gone flat? Also is it the same cylinders every time? One more thingto look at is the dist.cap may have a crack that you can't see, sometimes that doesn' show up untile certain temps. or loads. good luck.  

If it comes and goes then its probabley electrical in some sort. When you checked your cap did you see any moisture in it this can cause hte same thing. To just check it when it runnig good just spray a little water aroung the distributor and see if it changes if it does then hte cap needs to be changed. GOOD LUCK