'92 Chevy Lumina 3.1 running rough, under accelerating, slippage?

[cryptidalien]

Having a recent issue where my lumina would run rough on idle, and only vibrate during certain points while driving, noticed at 1500 to 2000 rpms, and when shifting to a certain gear, think it might be 3rd. I checked for codes and nothing comes up. The weirdness to me is the vibrations coming and going, and the intensity of it. It gets the most intense when I've got my foot heavy on the pedal.

Things I've done was check oil and trans fluid, both were good. Also cleaned up the throttle body half-hassardly, though I might give it another cleanse just to be sure. Any ideas on what might be going on?

Edited October 18 by cryptidalien
adding tags

[Schurkey]

The Usual Three:

1. Verify fuel pressure at prime, at idle, and under load. Most fuel pressure gauge assemblies have a push-button pressure release connected to crappy vinyl tubing. Route the tubing so it empties into a drain pan, then push the button while the engine is running. This simulates higher fuel demand if you can't check fuel pressure on the highway. Fuel pressure should remain steady even with fuel flowing down the pressure-relief tubing. TBI systems don't hold pressure when the pump stops running, but the other fuel injection styles should. How old is the fuel filter? Have you ever dumped a bottle of Chevron Techron Complete Fuel System Cleaner into the gas tank? (Recommended at every oil change.)

2. How old are the usual “tune-up” parts and procedures? Inspect/replace plug wires, spark plugs. Use quality parts sourced from an authorized seller (NO COUNTERFEIT PARTS FROM AMAZON, EBAY, OR OTHER SKETCHY SELLERS!) Be sure the ignition coils will reliably fire a spark-tester calibrated for HEI when the coils are fully warm, and misted with water from a squirt-bottle. Cranking compression test of all cylinders while the spark plugs are removed. Verify EGR, PCV, EVAP, and Heated Air Intake (if used) systems for proper operation. Verify electronic spark advance. Replace old O2 sensors unless you can PROVE that they're working properly—old O2 sensors get lazy, they don't provide accurate data, but they do provide “data” that fools people into thinking they're “working”.

3. Connect a scan tool (NOT a crappy “code reader”) and look for “codes”. More important, look at the data stream to verify EVERY sensor and computer output. Verify fuel trims during the time that the vehicle is not running properly.  “Codes” have official diagnostic procedures that will be found in the service manual set for your vehicle.

[Schurkey]

3 hours ago, cryptidalien said:

cleaned up the throttle body half-hassardly

Halfhearted.

https://www.merriam-webster.com/thesaurus/halfhearted

Haphazard

https://www.merriam-webster.com/thesaurus/haphazard

 

So you've invented a new word incorporating both meanings.

Edited October 18 by Schurkey

[Vegeta]

Your 3100 tag is invalid;)  3100 is SFI and says 3100 on the upper intake.  Not your question, just who I am.

What you describe is what my cavalier wagon has had issues with forever.  Bad mounts.  All of em.  That, and my output shaft seal is bent and I think the bearing or something else is bad.  Destroyed my passenger side axle every year or 2...gotta replace my trans and new half shafts.  So, check your half shaft alignment because it could be mounts, transmission output shaft, or half shafts.  

If its really just the motor and only at 1500-2000 and idle, leaking EGR?  Not fuel or spark, because those don't get better under more RPM/load.