I have a 1993 Blazer Tahoe Lt that hasa rough idle once warmed up. It almost feels as though it wants to stall out when sitting at the lights or a stop sign. I've changed just about everyhthing possible such as
Cap & Rotor
Plugs & wires
EGR valve
Air filter
Fuel filter
Fuel pump
the spider assembly was changed and has about 60,000kms but had the rough idle before it was changed. The only things that havn't been changed is the Cat convertor and the whole distributor. Not sure what else could be the problem. Any ideas?

 

You didn't mention anything about the fuel pressure regulator being changed. If you have the CPI motor, hook a fuel pressure gauge to the schraeder valve on the fuel inlet line and turn the key to the 'on' position. Pressure should be ~52-62 psi. Turn the key off and see if the pressure drops more than ~2-3psi. If it does, you have a bad FPR. If it continues to drop over the next few minutes, you have a leak in the lines inside the plenum.

 

Where is the schraeder valve and fuel inlet line located?

 

Ok so the pressure was tested by my dad who owned the vehicle before me and said it was fine. So that's not the problem.

 

what did ur spark plugs look like when u changed them?

 

Not to sure, my dad changed them. He did however tell me today that one plug hasn't been changed cause he couldn't get to it. I wonder if that plug isthe problem?

 

All plugs look fine and changed the last one. Pretty much stumped now.

 

hmm have u double checked the spiders just incase?

also if i remember correctly i think someone had mentioned that they had a rough idle when their catalitic converter was goin. not sure on that tho.

 

im sort of having this problem as well, it is begining to start. hopefully when i look at the egr valve, seafoam the blazer and change the oil do the trick.

 

I'm having the same problem and from what I've found searching more often then not it is either the crappy EGR valve or the fuel pressure regulator that is located on the CPI or otherwise known as the spider. Here check this link, https://blazerforum.com/m_65358/tm.htm
Take off the thing ontop of the intake mannifold and look inside to see if one side of the mannifold is really clean from fuel wash. It doesent take long to do and it's worth checking.
Otherwise check and clean the EGR valve.

And I don't want to steal your thread here, but does anyone know what footpound to tighten the intake mannifold bolts down to on a 4.3 1993 CPI 4x4 s10 blazer engin too?