okay, swapped a y8 back into my car finally so it can be reliable, to find out it's been more of a pain in the *** then a built one

PROBLEM 1: anywho, i drive my car for X amount of time, stop at a light and it will vary rpms in the idle. It'll go to 1700, drop to 1000, then to 1700 drop to 1000 etc about 1 time every second. NOW, if i brake, have it in gear, and slowly release the clutch to drop the rpms and hold it at 1000 K, it will eventually stay there for a few minutes. not a big deal, but onto problem 2.

PROBLEM 2: If i let it sit and idle like state above for maybe 2 minutes, eventually the car will idle from 1600-1700 dropping 100 rpm very fast, so back and forth from 1600 to 1700 about 4 times a second. dah dah dah dah is what my car sounds like. bad example i know but anyway, heres the thing. I havn't been able to tell if the cooling fan doesn't come on, but if i let it idle like this(varying 100 rpms) the car overheats. SOON as i start driving, the damn thing will cool. I realize some of this can be a vacuum hose leak or something, but it just seems so strange.

*Idles from 1700 to 1000 when out of gear at a stop AFTER driving.*
*Car then idles after 2 minutes from 1600-1700, about 4 times a second*
*Car overheats while idling from 1600-1700*

Thanks in advance for anyone who at least reads all that jargain! Thanks everyone, hope someone has had the same problem to help -Jeff

 

any thoughts?

 

check your iacv valve. There is a plastic piece within the sensor that might be broken. Sensor valve could be dirty with carbon and soot. Faulty sensor.
Air with the sensor causing jumping idle.

 

iacv valve? wheres that at never heard fo it haha

 

back of the intake manifold....2 coolant hoses going to it and one sensor....

 

ty any idea how much to replace the sensor?