I think I've figured out the running issues in my 2000 4.3W Blazer.
Running issues I had:
Lack of power when trying accelerate aggressively.
Falling on it's face at times when taking off from a stop, or stumbling to a stall if trying to rev engine while in neutral.
Back fires.
Bucking sensation when cruising at highway speeds, no power for passing gear or pulling on upgrades.
Engine and RPM's racing but not going anywhere fast.
Random stalls.
The fix:
Replacement spider injection unit AC/Delco 217-3028, $267.26 from amazone.com. Free delivery, included bracket, fuel regulator, and all required gaskets.
Previous attempts:
I replaced the Champion Plugs with AC/Delco's, a little more pep but no fix.
I picked up a distributor drive gear for $45, pulled the distributor and mine looked new so I returned it. I did add a shim to the gear on my distributor to take out some of the end play. Still no fix.
In preparation for the fix I had purchesed:
Timing chain set $32
Timing cover $58
Oil pan gasket $$28
Intake plenum gasket set $22
Luckily I started with the spider unit first. Other than a slight miss at idle it runs like new. Glad I didn't replace the timing chain first or open anything. I returned all the unopened parts. I'm sure the slight miss is the Autozone wires that were put on it when the replacement motor went in. As I was reinstalling the coil wire, it wouldn't snap on, I found another wire in the garage that snapped on tight, if the coil wire wasn't making a good connecton the plug wires may have issues also. Tomorrow I'll pick up a better set of wires and hope it fixes the miss.
Good luck to all fighting the Gremlins.