(1991 4X4 S10 Blazer 4D 4.3 fuel inj.) I have aftermarket gauges, when I come to a stop light it idles so low I have to step on the gas a little bit to keep it running. The check gauge light comes on and the temperature gauge that's in the dash (not hooked up) goes berserk up and down. It acts like I'm not giving it enough gas and when I try to even it out it acts like I'm giving too much. Please help.

(1991 4X4 S10 Blazer 4D 4.3 fuel inj.) I have aftermarket gauges, when I come to a stop light it idles so low I have to step on the gas a little bit to keep it running. The check guage light comes on and the temperature gauge thats in the dash (not hooked up) goes berserk up and down. It acts like im not giving it enough gas and when i try to even it out it acts like im giving too much. Please help.
It also stalls out from time to time, it will be running but have no electrical power for a second then it kicks back on. I noticed when I stop and the gauge light flickers the oil pressure drop instantly to 20 then when I start going again it goes back up to 40. Anyone have any clues?

It also stalls out from time to time, it will be running but have no electrical power for a second then it kicks back on. I noticed when i stop and the gauge light flickers the oil pressure drop instantly to 20 then when i start going again it goes back up to 40. anyone have any clues?
There is a screw under the left side of the dash that works loose. On that screw is ground wire for the cluster. It is above the park brake pedal. It is a seven millimeter scerw that holds a ground wire.. pointing straight up, and is very near the edge of the lower plastic cover. Check that first and let me know.

I found the screw and it is tight, have any other ideas? I've changed the TPS and IACV and it still don't run right.

You may have need to view engine data to determine what's out of range. You've check the battery connections and they're all good clean and tight? No signs of corrosion?
You may even have a failing ECM. How's the fuel filter?
Try installing a redundant ground from the block to the frame and to the body... just a thought.

I'm going to change the filter tomorrow when I get paid, but yes, it has all good connection and no corrosion

Ok, I changed my fuel fliter and everything above plus oil change, got any other ideas? I have no clue

Test/replace the Ignition Control Module (ICM) and coil. AutoZone will do this for free. I suspect the ICM may be bad. I recommend replacing both items on all vehicles that have 120,000 miles on them, or are at least 10 years old. Ensure you only use ACDelco spark plugs and that they are relatively new.