I have a 95 S10 LS 4dr, 4wd, 4.3 Vortex "W" 230K miles,
After the engine warms up, when I stomp on the gas, like when I am passing on a two lane road or on an on ramp, the engine falls on it face, it seems to die, go again, and die. If I hold the throttle down for more than a few seconds, it runs rough and I have to shut it off. If I let up right away it fully recovers.
If I steadily accelerate, I can run it up to 90mph, no trouble. It is only under sudden acceleration that it act up. Any ideas?

 

Lots of ideas: It's either fuel or spark.
There's no SES lite?

If you havent changed the fuel filter in a while, I would start there.
And borrow a fuel pressure gauge. And check key-on fuel pressure for about 60 lbs, check that it holds pressure above 50 for over 5 minutes.
Then you need to determine if it will do the same while in your driveway. IE hold brakes, and give it gas. If it stumbles, what its the fuel pressure when it does that? If it maintains over fifty.. {60 minus manifold vacuum} then look at ign.
Old days what you are seeing was sure sign of bad coil.. flashover. Not quite as simple now but a good place to start... AFTER a full tuneup of Ac Delco cap rotor wires and plugs.

BTW.. what are the tach indications when it does that stumble? If it seems to go nuts {higher} then definite ign probs often in the distributor.

 

I guess I should have mentioned, I just did a lot of work on it. New fuel pump, new filter, new intake manifold gaskets, New cap, rotor and wires, The plugs are platinum with less than 30k miles, And no check engine light.
It started doing this prior to the work and is still doing it. One guy mentioned the rev limiter? is that in the Motor Control Module? or a separate part? As google searches only turned up rev limiters for 92 and older models. Now that I say that, it only does it when it kicks down a gear. Also, I had to fix the pigtail wire going to the crank position sensor. The wire had chaffed through, just below the connector where it plugs into the harness by the AC pump.

 

Also, during all this work, I dropped the spare out and later, in a hurry put back, it caught on the rear brake line and broke it. I have bled the brakes using a vacuum bleeder. Does anyone know how to reset the brake balance switch under the master cylinder?

 

It may be that, after all that work, the system notices the timing cam angle hasnt been set to '0 deg'. Note that is the last step in reinstalling a distributor
CASE 'relearn':
https://blazerforum.com/forum/tech-a...-timing-24373/

It should be noted that some users here have had Duralast parts run bad right out of the box.
'Platinum' plugs mean diddly.. sorry. Bosch plats usually dont work well but under different conditions.. meaning at low-load cruise missfires.

Also a new thing has come up.. new to me, anyway.. and that is the vents in the dist base {beneath rotor}.
Again.. can you make it happen in your driveway or not.. and what does the tach do when it happens?
Rev limiters are purely digital - part of the ECM- and operate on the same signal the tach 'sees'.

 

Don't use Duralast parts, everything comes from Carquest. Not for sure but I believe they are AC plugs and they looked good. Unfortunately this model doesn't have a tach.
It was doing this before the work too, although now that the weather has cooled to below a hundred thousand degrees (I'm in Southern Kansas and we just had the hottest summer on record) (gotta love that global warming, yeah right) it is not as bad. And it runs just fine normally, I am even getting 20mpg up from 17mpg.
Would a slipping transmission cause the engine to rev high enough to activate the rev limiter? Like I said it only does it when going into passing gear.

 

BTW, thanks for the input. It is appreciated.

 

I guess I should have updated this a while ago, but it slipped my mind

Come to find out, when the mechanic replaced the crank position sensor he failed to add the little .020" shim washer. I did that and it fixed the problem