1993 Blazer Idle Issue

I have a 1993 chev Blazer 4.3L Vortec "W" series. When I pull up to a red light or stop sign, the truck idles good for about 10seconds than starts to idle really rough and shake violently. Upon take off it sputters like fuel starvation or a bad misfire than takes off. The list of things that have been replaced is quite extensive.
-Spider Injection Assembly, lines & all (Replaced about 40k ago)
-Fuel pressure regulator (Replaced 3k ago)
-EGR (Replaced 40k ago)
-Fuel Filter (Replaced 5k ago)
-Fuel Pump (Replaced 20k ago)
-New plugs, cap & rotor (Replaced 20k ago)

I went ahead today and changed plug wires with some Delco''s, air filter cause it was due time to be done anyway and saw that the air temp sensor in the air intake tube was all gummed up so I cleaned it with some CRC carb cleaner. Well not only did none of what I did make any difference but now the service engine light is on. WTF?
I also noticed that on the drivers side right below the middle plug wire there is an electrical plug that is cracked. Any ideas why now the engine light is on as well?

the burned connector is a nox sensor..i had the same thing....check your cap..all my electrodes were burned...in only 6 months too...

That's the knock sensor.

Check codes and post back code no.