Greetings all
91 s10 blazer 4.6 automatic.
Idles rough, keeps dropping rpm then catching up. If left alone without more gas, it will eventually stumble so much it dies.
Accelleration and high RPM performance seems normal (though this is not my truck so Im not sure how much power it has normally)


Replaced plugs and wires
(old ones were very old, rusted to the block and wires were still in stock harness, major corrosion at connections. Gapped new plugs to .35, cleaned connections, applied dielectric grease and anti-seize at respective points)

I HAVE:
Removed and inspected fuel filter.
appears fine, blow-through test with little resistance.
*I have heard there is another fuel filter near the carb?*

Check air filter, clean carb
Air filter is K&N, no blockage. used carb cleaner on the visible parts of the carb. There was brown tinting, but no sticking parts.

Check IAC valve
Removed and cleaned IAC valve, no visible damage.
*Is there a way to test the functionality of the IAC?*


I have NOT:
Removed Distributor cap, gap rotors (no gapper available, perhaps autozone will trade me one for my ID for a while?)

Cleaned MAF

???


I am an intermediate mechanic, our of necessity, I usually fix my own cars, since i have had very bad luck with mechanic shops (usually end up breaking something unrelated, like the back door of my 65 Corvair while tracing a bad tail light wire.)

Any help would be appreciated, especially information on the secondary fuel filter I have heard about.

Regards, Hector

 

4.6? I think you mean 4.3
but what brand did you use for plugs and wires?

 

Oops, you are right, it is a 4.3L. I used Omnispark wired (i know, i know, but anythings better than 20 year old stock cables)
and NGK Iridium spark plugs

 

Since the wires and plugs were so old, I would do the cap and rotor as well, ACDELCO