idling problem

the car idles at the normal idle then drops to like 400 then idles itself up to like 1200 to 1500 then i give a little gas and goes back to normal and it just keeps doing it what could it be?

does it almost die out and does it happen wen you slow down and come to stops?

sometimes when i hit the brakes it drops to like 100 so maybe a vacum line? but it dosent do that all the time

yea same here man..my vacuum lines are all niggerrigged. did this just start happenin tho?

yeah after i changed out an injector it ran good for a day and then this started happening

yea i doubt it was the injector. didnt u tell me ur whole motor was fucked?

i thought it was

Do your brakes feel abnormal? There is a check valve at the brake booster, when they go bad it creates a bad vacuum leak. Check the valve, make sure it only allows air in one direction, a quick check would be to plug the vacuum to the booster and see if it changes anything. Vacuum issues are a pain to find, it would be worth taking it to a shop with a smoke tester. A smoke tester will show you every leak in a few minutes, eliminating a lot of headache.

Also, what engine is it? Do you have any kind of intake? Stock ECU?

ka24de with a injen intake and stock ecu

it drop to like 100rpm but it doesnt do it everytime just every once in a while

get some carb cleaner spray around the intake manifold if there is a leak through there you should notice the rpms raise. I had a problem similar to this with my s14 turns out it was a vacuum leak and bad intake manifold gasket after the maf causing a fucked up idle upon taking the upper intake manifold off all the hoses were cracked and leaking

idle controller? went bed? check your intake, for leaks or cracks.