Vortec 4.3 Idle

Well ive heard that the vortec 4.3 from consumer reports that the engine has some idling problems. When i first got my truck and it idled at 1500 rpm i didnt really think to much of it, but now when i turn on the truck and it idles at 2000 rpm and at 1500 when in gear, i started to get kinda pissed. I thought it might be my air flow so i bought a new k&n air filter and it still gave me problems. When i read a chiltons GM manual i checked to make sure that all my hoses were ok and in good condition especially the ones from my master cylinder (apparently that can cause the engine to idle high) I was leaking antifreeze but that was a hole in my radiator so i replaced that. So i know its not a cooling problem. Please if anyone can help me i would just like to know what you guys think the problem is, im really not sure if this is what the consumer reports were talking about but i really dont think that it is.

I would start by putting some fuel injector cleaner in the tank. It cleared up my problem and now I use it like every 10th fill up. Change your fuel filter. Look closly for vacuum leaks at the hoses and connections. You never said what year you have but I change all my hoses like every two years. Its not that hard just pick up some of each size and change em one at a time so you dont get em mixed up. How long since your last tune up? Open the hood in the dark and look for bad plug wires. They are EZ to find that way.

Could possibly be a bad coolant sensor, reading way below actual temperature, telling the engine it's running cold so it would go on high idle. Or you could have a bad idle air control motor that actuall controls the idle. Just about need a scanner to see what's going on here.

Remove and clean the IAC valve.
or replace IAC with new for about $25.
IAC=Idle Air Control.

its a 1994

If your truck has the 4.3 Vortec with CPI injection, the IAC will start at $69 bucks. If it is a throttle body type it is much cheaper. Clean it (IAC)first, and check for vacuum leaks, will really cause idle problems. As stated before, temp sensor could be goofing up or even tps (throttle position sensor). Be sure to unhook battery before cleaning any sensors.

thanks everyone i'll get right on that and keep you posted. Really thank you all very much.

Vacuum hose has rotted off somewhere.

IAC valve is stuck.

hi i have a simular issue my 92 s10 4.3l tbi runs fine until its warmed up then it jumps upto 1900-2200 rpms, ive checked the vacuum lines and none are bad but if i unplug the vacuum sensor when its warmed up the rpms go down to about 1000.

i cant figure it out ive put another vacuum sensor on it and still does it the sensor ive changed is beside the throttle position sensor{on same bracket}

i just found out the issue with mine it was a bad coolant temp sensor, i changed it out and now it runs great