Coltc,is your PCM/main computer checked out to be fine?
mine was fried,issues very similar to yours & i spent almost $1000 bucks by time i got around to that part.

 

I have had a problem with my Blazer 95 4x4 4.3, 4 doors, vortec, and the 8th vin digit is W. 4 days ago the check Engine soon light turned on, but just for 1 hour or less, the blazer was strange, and the car had some tugs and jumps... but the light and the problems are gone.. Can I get the codes with no check Engine soon light?
Also sometimes (cold weather below 40's) My blazer start good, but in and after the trip (usually 10 to 15 mil) the revs are between 1200 to 1600... The problem usually end just after turn off the engine and restart it again... Some ideas?
The last one. Some advices to buy a good scan or code reader for Blazer 95 4.3L, and serie W... there are a lot , I need some advices...

 

First check your egr valve see if its stuck can cause problems like that as far as a code reader for a 95 try autozone theirs will usually read it if not try an actron elite or equus they pull obd I and II yours could be one of the "obd 1.5s" some 95s are even if they say obdII under the hood. Those scanners are expensive (200 to 400 bucks) thats why I recommend trying a parts house first or even take it to a mechanic and let them read it. Yes u can get codes without the ses light on they are "ghost codes" that are saved in your ecm. Hope this helps u some.