I'm banging my head against the wall now!It starts instantly and idles steady, but when you rev it up, it "clogs up" around 3000 rpm. After a few good stomps to the floor, it will "clear up" and redline easily. The only way it will drive on the road is being very gentle on the accelerator....too much gas and it will start bucking. It's died a few times on the road and won't start for a while unless it's hit with starting fluid.
It's a 1992 S-10 Blazer 4.3L vortec.
I've replaced plugs, wires, cap, rotor, thermostat, air filter, fuel filter, and fuel pump. The catalytic converter looks brand new, but it does need a muffler. I can't imagine an exhaust leak would make it run so crappy? I'm going to replace the muffler tomorrow, but I doubt that will fix the problem.A mechanic said it was probably a bad sensor or vaccuum leak, but the lines all seem fine. I don't know what to do next, other than take it to a Chevy dealer.

 

I'm sure someone will come in and say, check the fuel pressure. Did you have the issue before you replaced all that stuff? Wires hooked up properly?

 

when your revving it, its in park?

as jason said......fuel pressure problems cant be good......

 

Yes, it is in Park when I'm revving it.
and yes, the problem was there before replacing the parts.
I ran it very low on gas before the problem happened, that's why I replaced the fuel pump/filter, etc.
I haven't yet checked the fuel pressure, but will probably try that before I give up.
Thanks for the ideas

 

Test your throttle position sensor. You should have around 0.5 volts with the throttle closed, and it should increase steadily to around 4.5 volts at wide open throttle. If you see it drop to zero at any point along the throttle movement, you have a bad TPS.

 

i was going to say check the TPS. however, it could also be some sort of vaccuum leak, causing it to sufficate. OR, it could be a fuel pressure regulator, causing it to choke. when you replaced the fuel pump, did you replace the pulsator, as well? that could have gone bad, although rare (but anything's possible i guess). check the fuel pressure regulator, too.

 

Did you try the control module on the distributor? I have a 92 and this pass fall after driving it for about an hour it would start to die on any kind of accelaration. I would have to coast around just barely touching the gas. It would buck like it was needing gas and sometimes pop and then die if I floored it. After replacing the normal stuff, caps,plugs and rotor and checking the fuel pump pressure, did I go to the control module. After replacing the module it runs like a champ. module is about 35.00 to 40.00 at Pep boys.

 

but i thought if the control module was bad, there wouldnt be any spark.

 

You know thats what I thought too! Ironic though. When I took off the module, what I noticed on mine was that the silicon grease for the underneath of the module was either never put on or just evaporated over time. I think what was happening was the module was heating up after continuous driving (for me it took about an hour). The grease is used to disperse the excess heat to the base of the distributor. thats why you always get a tube of this stuff. I always thought the module was either good or bad with no in betweens. I was wrong with that assumption. When my vehicle acted up to the point of not running I finally got out put a spark tester on a couple plugs and could see they were not firing under load. so for me changing the module was alot cheaper than replacing the distributor.......

 

The Ignition control modual controls the timing of the spark. The spark will still happen, just at the wrong time.