ahemdave_90_blazer said:also, pull the distributor cap and make sure the shaft bushings are tight, and that the pick-up coil reluctor is not spinning on the shaft, i've seen several doing that with one of these problems, both require a dist. replacement
So we are going to: check the distributor stuff first, the guy helping me is just a little worried about making the timing worse by taking the dist. out. I don't know how that could happen but he's a nice guy just for helping!
So after that we bought a new EGR valve and that is plan B, then on to the fuel system! My mechanic said he checked all of the sensors including the coolant temp sensor so we are going to start heading towards areas he didn't check
If all of these things don't work, then going to start retesting all the sensors we haven't replaced. Any more ideas would be greatly appreciated because so far we have several mechanics scratching their heads while they sit around with a drink in their hand. Thanks again!! 
--they go bad quite often,and they are a pain to replace--they are located UNDER the intake plenum in the lifter galley..we usually save any we can from vehicle thats being junked,so we can "test" it by swapping the "good used" one in ,rather than spend that much to find out something else was the problem..
he said it was TBI, not CPI(w/"spider")diesel4me said:If its a V6 4.3. litre,it might be a faulty fuel distribution device(some mechanics call it a "spider" because it has 6 hoses coming out of it,and looks like a spider!)...its about 400 bucks from a dealer--they go bad quite often,and they are a pain to replace--they are located UNDER the intake plenum in the lifter galley..we usually save any we can from vehicle thats being junked,so we can "test" it by swapping the "good used" one in ,rather than spend that much to find out something else was the problem..
Symptoms range from surging,stalling,running like a plug is fouled,loading up,black smoke,etc..but EGR valves are noted for causing similar symptoms too--make sure if you remove the EGR to see if its passages in the engine aren't plugged with carbon chunks--we've seen lots of that on 4.3's too...good luck..![]()
--now I have to learn all the "new" stuff,and forget about points,dwell,carbs,.. sigh!.. 