My truck starts and then immediately stalls
 

If I don't keep in the throttle immediately after start up it will stall a lot of the time. It doesn't do this everytime or if it sits for a while but if I drive it and then stop off at a store or something and then go to start it back up it gives me this problem. I notice it idles about 3-4k RPM's when I stop at a light or something too. Anyone have any insight?

Sounds like the IAC (Idle Air Control) is bad.

That's about $150 for a new one, right? Wouldn't that throw a code?

No it doesn't throw a code. You could try cleaning it some people have luck with that some don't. Search the site you'll find something on it. Def sounds like the IAT though.

That sounds a bit high. You might get lucky and it will work right after removing it and cleaning the guts with brake parts cleaner.

I still have the same issue BUT now it stalls occasionally while driving when coming to a stop. Then when I turn the key to start it back up, the instrument panel guages "peg" themselves for a second and then back to zero before I can crank it. Also, occassional while idling, the guages pulsate or jump back and forth. Is this something that could involve the Idle Air Control Valve? Is it an electric problem? I need help before I start blowing money on parts.

What have you done so far? Did you change the IAC?

I took off the AIC and cleaned it with brake parts cleaner and re-installed it and now it runs rougher and idles at 3000-5000 RPM's or it just stalls. Then I unplugged the connector while the truck was running and it made no difference in the idle speed whatsoever....so my conclusion is that the part is bad. Would you all agree with that?
Also, in the last 4-5 days when getting off the freeway after 30-40 minutes of driving, my truck would stall at the end of the off ramp everytime. Then when I restart the truck, all my radio presets were erased and I had to reset them. Could these problems be related?

I still need help guys!!

OK, I checked on the price of a new IAC and it's between $100-150. It is very specific for the 4.6 for 2002 for some reason.

A friend suggested it could be a vacuum leak too and said to spray starter fluid on the vacuum lines and if the RPM's rose up then you found your leak. Sounds logical but I'm no mechanic so would any of you guys agree with the starter fluid theory?

Also, if you guys could point me to a place where I can possibly get a new IAC for a 2002 4.6L (not 5.4L), for a reasonable price, I would greatly appreciate it.

Thanks

Did you ever get this fixed ??

I imagine that the OP doesn't have the truck anymore, or issue is cured....note the post date

The OP last visited this forum almost four years ago. He never followed up on his post.

Yeah but my truck is 32 years old, not much traffic out in cyber space on 85’s these days, they are mostly crushed I’d say.

But all the same, all documented information on symptoms and solutions are very valuable to me, no matter how old the thread is. Just a shame that most just drop off after they have found enough, or solved their issues.

I spend the time to read pages of threads, get to the end, and nothing, so I take the 3 second it takes to ask the questions. I have learned over the years though, to read the first thread, then go to the last thread, and work my way from there.

I have to say, I have learned a lot reading the older post over the years, they can be very valuable, mostly due to the regular folks like yourselves that selfishly give your time to ask the right questions and provide your experience to these dead-enders.

I thank you for your time……..

If you have a start-en-stall each time but will run ok otherwise, the intake air controller is not controlling idle.
Often that controller has a blocked internal air bleed port that can cause the issue.
The only way is to replace it because it can't be cleaned inside the device.
It also could just be an intermittent electrical connector.
Once those engines are started they will run afterwards even if a connector goes open but will not start again after shutdown if the open remains.
Hope it's that simple.
Good luck.