(RPM) Problem HELP PLEASE

[Russian318]

Hello everyone!
I have 98 318i (M44 1.9L) It had problems ever since i got it I dont have money to get newer car so i am trying fix this one up...
The problem i am trying to solve is my RPM issues. They jump up and down everytime my car cold and also when it has been driven for a while.
1. I replaced my icv... calmed the rpm down a little but did NOT solve the problem...
2. Changed my spark plugs... still same.
3. Cheked my SP wires didnt do it eather...
Before i start spending any more money, could anyone tell me what it is pleeeeease???
Is it o2 sensor? Vacume leak? or is there other things?
THANKS GUYS ANY HELP WILL BE APPRECIATED!!!!!!!!

[witeshark]

Have you checked the intake boot for cracks? This was the cause of a very similar problem on my E30.

[thekid]

Cold and driven a while means it is happening all the time right? It won't be an o2 sensor without a CEL unless you are having other issues. Is it an auto or manual? If manual does it only happen at a stop or at any time at all with clutch in/in neutral? You can check the air box visually and you can check for the vacuum leak by spraying slowly over hoses etc with carb cleaner while the engine is running. If the idle races when you spray you've found a leak.

[Russian318]

Cant believe i forgot guys sprry, it is a manual.
Ok so every morning when i start it up and it idles at normal 650-700 rpm. If gas it to about 2000 and let off, needle drops to 450 then 1000 and back to normal. i live in colorado and mornings here are really cold so i let my car sit for a couple minutes... when i put it in reverse and start baking out, as soon as i press in clutch it dose same as i listed above first 5-10 minutes of driving it doese it then it calms down... And like i said since i replaced my ICV it is not as bad as it use to be so there is probably more to it. And yes i replaced the boot with the brand new one, got rid of my stock air box and put on a cold air intake. other issues i have is sometimes when it is too hot outside, i would start it and it dies, then do it again it starts normal. It happends really rarely though. If you guys need more details just tell me lol THANKS FOR YOUR HELP!!! Oh ya is it suppose to idle at 700 when it is cold? because my gf has a mitsubishi eclipse and when you start it up it idles at 1500 and as it worms up it goes down to 800.....