My engine has a high idle why?

302cid, auto trans 4x4-truck running 2500 idle, wouldnt kick down so I turded off. Now wont start. Have spark to plgs, fuel to injectors any help apprieciated-do not have tester for code and really cant afford one. Will most likely go to junk yard for parts, the usual, low income

Thanks rasmataz ILL give it a try in the morning.
One thing I forgot to add, when it was running sometimes it idled fine, then about a month ago the idle started jumping up and down and wouldnt kick-down manually. Once shut off and started up again it was usually o.K. For awhile then out of no-where it'd start jumping up&down again.
Thanks again

Also I cant find the iac motor, I think its dirty because when I start the truck it idles high for a minute or so, I mean like 2 thousand or so. If you have any good advice I would be very thankful. Thanks chuck!

When truck is turned on it has a high idling until I quickly set it on drive, then it goes down to normal idling. When at a stop it also gets a high idling. Please help.

This has been an ongoing problems for years.

At Idle, the engine will sometimes Idle at the normal 500-800 rpm but the engine light comes on and stays on, (no code flashing). However! When the engine feels like it, the engine will sometimes start Idling high at 2,000 rpm at which point the engine light goes out and does not flash any codes.

Years ago, I took it to the ford shop and they said they replaced the intake gasket and that "seemingly" fixed the problem for about four to five months. Then it went back to the same issues as noted above.

I think it is very odd that no codes are thrown and the engine light acts as noted above. And being a rather good shop mechanic, I have done everything I know, and replaced quite a few of the sensors, map, idle, oxygen, exhaust, etc.
Nothing improves it.

The one thing I have noticed is that many of the 1985 to 1993 Fords (302) right passenger side exhaust manifold has a factory (defect) crack that appears between the two middle exhaust ports and ford never recalled this defect. Thus I ponder if the exhaust oxygen sensor is causing the issues due to the leak in the exhaust manifold.

I know everyone yells vacuum leak (somewhere) but its hard to believe that with all the maintenance I have done (and a four month old new intake manifold replacement) that the vacuum leak is the issue. If that were the case, then it seems that there would be a continuous high Idle, not an intermittent high idle one week, low Idle the next week.

Any other thoughts or suggestions?

Thanks for the input and insights.

Even though it has its common colds and normal hiccups, I Love this 30 year old "Ford" truck as it hast failed me yet. Stuck in the 1970's and 1980's I guess.

As I stated previously, this has been ongoing for years (at least two decades) and In such I have went through this engine and done the carb-cleaner test in the accessible areas, meaning its hard to do the test in certain areas or around the back of the engine near the fire wall. Or without spraying other components.

Best of my failing knowledge and feeble mind, carb-cleaner and rubber hoses (maybe the nylon/plastic ones as well). Some don't like carb-cleaner as it can/will melt and brittle certain types hoses; possibly causing more problems and vac leaks. Thus as I stated, I have avoided those "blind" hard to reach and other areas where the spray and/or over spray cant be controlled. In such, WD-40 was my alternative in addition to carb-cleaner in certain areas as it too will indicate a leak.

In saying that, the one thing I have never done is check the brake booster for vacuum leaks as that eluded me, but that is a good call. So that might be the culprit or a contributor at any level, and definitely something that should be looked at just from the maintenance end as its a vital component.

Being that its an older model, maybe I will replace some of the vac-lines just for the hell of it as I agree they look a bit old, rough and dirty (but intact). But who am I to claim I can see vacuum leaks. It just seems that vac-leaks would be consistent, not intermittent when it comes to the idle issue.

Since this is a project restore and not a desperation of an everyday commuter, I will climb back under the hood and play around some more when time allows.

But as for the other I posted, Ford seems to have avoided the "right side exhaust manifold casting crack" that appears after certain model/year trucks of this era as I have been under the hood of many, some just to prove my claim, and every one of them had the casting crack in the same area!
In such, there is an Exhaust Oxygen Sensor down below where the two sides of the exhaust union.
Though this would be a constant pressure side (exhaust) and very little O2 ever coming or leaking in to the exhaust and reaching the sensor, I cannot help but to factor that in to some "slightly off" reading sensor reading. Outside of that, any backfire or escaping heat from the hot gasses, seems to be of concern as it might cause a flash fire or undue increase in heat to that side of the engine, thus causing problems to electric and other over a long period of time. But that is just my ramblings of insights.

It is also my belief that this crack occurs due to casting and stress from the weight of the exhaust pipe and components, but due to the age of the trucks effected, that issue is mote and speculation now. Lets just agree that Its not something a 6 pack and JB Weld or Pipe Wrap will fix. LOL
Maybe a header swap would fix the old beater issue when and if you have the money for the fix.

Lastly, and for others with plastic line leaks per the link you posted; some of these lines seem to be glued or formed together to the rubber connector. In such you cant remove the connections to easily replace. While you can cut and splice the hose my alternative is the "Liquid (rubberized) Electrical Rubber" (Star Brite Liquid Electrical Tape) and/or as well as electrical shrink tubing that can be used to cover/seal any small crack as to seal it up or after splicing as to ensure a better long term seal.
Still I recommend an entire replacement of the hose as this (and splicing) is only a short term fix and is not very pretty.

Thanks again for the Insights.

I will double check the brake booster.

My truck idle will go high then shuts off.