i have a 90 s-10 4.3 and cant seem to keep it running at a red light and shakes really bad like mis fire but i have replaced my cap and rotor, my coil and plugs and wires and i can her my fuel pump kick on when starting does any one have a clue please let me know its my only vehicle and i have been standed so much HELP!!!!

 

I had the same problem with my 89.
the computer was not working, it wasn't throwing any codes either.
That is the bad thing, you can't tell your computer is going because it
doesn't tell you.
Also check the egr just in case.

 

try pulling off the egr valve and check to see if it is plugged with carbon,or get ahold of a vacuumpump remove the vacuum line from the egr diaphram and apply vacuum <with engine running> if engine stumbles or stalls its ok if nothing happens its blocked