Hi everyone, I'm new here

Firstly I want to tell I’m not completely comfortable with English language, and if I have makes mistakes or if something is wrong with my message, I appreciated if you can stay polite and send me a private message to advice me about my mistake, and after I’ll correct my post if some part is wrong.

Now I will tell my problem with my cavy, it’s a Z24 1999. When I start the engine on cold start, he start really well but after the engine start to make some “up and down” and after a twenty seconds of run may be, he’s really well and all of that is over. He doesn’t do the same thing when I start it when the engine is hot. And other information, if I plug it (bloc heater) he don’t do this problem even if it do -30 outdoor.

I have changed all spark plugs for 4 brand new Platinum NGK last year, and I’ve “switch” the coolant sensor and the coil pack from my broken cavy for piece (he’s 196 000 kilometers) but nothing have change.

I want to know what can be the problem of my 2.4L ?

To help you I’ve put three video of his “up and down”

Thank a lot !

Last year :

http://www.youtube.com/watch?v=FYgiZipNMzc

This year :

Cold start just the RPM gauge : http://www.youtube.com/watch?v=nW1S25qofgY

Motor view : http://www.youtube.com/watch?v=I7TzeEQfj4o

Try cleaning the throtle body and the idle air control valve with a throtle body cleaning spray that should help.You could add a fuel injector cleaning can when you fill the gas tank. Other than that maybe fuel filter and air filter, just my 2 cts. BTW Welcome.