I have a 1994 S10 Blazer, with the vortec 4.3. Ever since I got it 6 months ago it never ran perfect. Replaced the O2 sensor a couple months ago and that helped but never fixed everything. Over the past month its gotten worse though. It starts hard, seems to be running rich, has really black exhaust that stinks, get horrible milage and sometimes when you take off it wants to stall.

Any ideas? Could my fuel Injector assembly gon bad, or what?

I have a 1994 S10 Blazer, with the vortec 4.3. Ever since I got it 6 months ago it never ran perfect. Replaced the O2 sensor a couple months ago and that helped but never fixed everything. Over the past month its gotten worse though. It starts hard, seems to be running rich, has really black exhaust that stinks, get horrible milage and sometimes when you take off it wants to stall.

Any ideas? Could my fuel Injector assembly gon bad, or what?

TBI or central port injection/ Code W engine?
Several thing to you need to check.
EGR valve and fuel pressure leakage or leak down and engine tempt sensors.
Does it have the digital electronic egr valve?
Any codes set?