I'm having the same cold start issues, it's been getting down to freezing temp here and when I start my truck it won't staying running and IF it does it only stays down around 100-200rpm and then eventually finds its way back up. I normally have to hit the gas to get it warmed up once I turn her over so she doesn't die on me and when I do it makes a lot of unusual, I'm guessing, valve noise? My valves aren't that ˟˟˟˟ty but it does make what sounds like exaggerated valve noise at cold start when gas is applied. I'm doing a top end rebuild though (new head, cam, rockers, etc) so Ill be able to tell if it's just worn valves or not once that's done (hopefully this next weekend).

 

 

Austin - ok I'll take a stab. After 10 minutes your engine starts warming up and your idle should go DOWN as the engine warms up. Before you go and replace the idle air control valve, tell me this, do you get a "cold idle" when it first starts up. You can look for the exact spec, but your cold idle should be higher than your warm idle, so maybe 1200 rpms or so. And then about 900ish when warm. If your cold idle is not high enough, when your engine warms up and the idle air control valve closes, then your engine may stumble and die. So step 1, check your cold idle rpms and report back.

 

 

If by "my rpms are good" you mean you are getting a warm and cold idle, then I doubt that the idle air control valve is your problem, because it's entire function is to give engine a bit more air when cold to raise idle, then close when warm to choke off that extra air.

Check for vacuum leaks.

 

 

Ok, well then if I were you, I'd turn your idle screw to raise that cold idle, then hopefully you can get it to run when warm.

 

 

Austin - you still really aren't giving us any info to go on. Did you raise your cold idle with the idle screw? Messing around with it doesn't really help me figure out what you are doing. A cold idle of 800 rpms is pretty low, as your engine warms up, the IACV or Aux Air Valve as it is sometimes called closes and lowers your idle by choking off that extra air. From your limited description it sounds to me like your IACV is doing what it is supposed to do, but your cold idle needs to be higher. The way you do that is to turn the idle adjustment screw. I don't know if this is your whole problem or not because you aren't telling me much. After you set the cold idle to something acceptable (there is a spec for your truck, but I'm not going to find out what it is for you), then if that doesn't fix it, we can move on with the troubleshooting.