Idols up and down by itself - 1986 Chevrolet Camaro

Testing , know what to check .
007 Idle Speed Problems Scan Data for Idle

Why is it idolizing by itself when it's in park? What does that mean?

I had the same problem with mine! I spent what seemed like hours trying to figure it out. I finally gave up and just said, while I'm here I'll just do all my preventative maintenance checks and give up for now. I noticed while checking the radiator that the antifreeze was low so I added a little less than a couple of quarts, closed the hood, started it to move it back to the driveway and guess what? It fixed itself! I guess it was just low enough on fluid it was telling itself, "I need to warm up." Hey, maybe you'll get lucky and the same simple thing might be the problem. Also their is a (usually vac. controlled) switch located on the throttle linkage that allows your engine to de-accelerate "softer" instead of just dropping all at once when you let off the gas. I have seen these switches with age or dirt and grime, stick in a position that the throttle wont fall all the way down. A couple of things to check that my be a simple fix. Hope all works out for you!

If recently had cleaned your Engine or Air intake, it may solve itself in 2 weeks, try to go fast several times,
if takes longer than 2 weeks then your Engin air controller faulty and need to be replaced

bleed the cooling system coolant sensors wont read air the ecu will think its cold then hot then cold witch flucuates the idol

Radiator may also be partially plugged. This usually becomes evident mostly in the spring, when ambient temps start to rise. When in motion, air flowing through unplugged radiator is sufficient to keep temp down, but at idle, fan can't pull enough air by itself. Since outside air isn't as cold, heat transfer is incomplete.
I'm sure someone out there will argue about my method, but I disconnect lower hose and block off the radiator lower connection, then do the same at the top. I use one container of CLR and pour directly into radiator (if you don't have a fill cap, use upper hose opening instead of blocking it) slowly pour in water 'till it's full. Leave for an hour then drain, use a garden hose to blow water through from top, out through bottom till it runs clear Seal off outside of hose to get pressure into radiator, wrap rag around it), then re-connect hoses, re-fill with coolant. (engine running heat full on).Generally this will give you most if not all flow restored.

either the tps is out of parameters or you need to adjust the idle up a bit

i'am no expert on this car, but i would chk. the T.P.S. (throutle positioning sensor) there also may be carbon build up on throutle butterfly, not letting it close completely when you take your foot off the pedel.

LOOK at your throttle plate and see if it is wedged open. there is a piece riveted on that i have seen come loose and prop open throttle

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