Rough idle revs dropping trying to stall when cold

[Corasdad]

Please help my car keeps trying to stall but doesn't when I cold start it, the revs sit about 800rpm but flutter up and down, when it's down it trys to stall.
I have cleaned the icv and can feel it vibrate a little so I don't think it's icv,.
I can't hear any air leak but don't know how to test it properly. What else can I test I know it could be a sensor but that's deep in the engine so not sure how to test that.
My engine is m43 with m40 head ( don't know why)

[flybynite]

To look for vacuum leaks either do it the correct way with a smoke tester and watch where the smoke gets drawn in or do it the way most people do and spray brake/carb cleaner (sparingly) around the intake, if the revs rise then you have a vacuum leak. Obviously harder when isle is rough.

Otherwise I would check usual suspects, plugs ht leads, air filter and make sure you have clean fuel.

Difficult to be specific as I don't really know 4cyls that well and we don't really know what the engine is wired up as for things like O2 sensor etc.

[BenHar]

What year and engine?

Ben

[Corasdad]

Car is 1990 no idea what year engine is as somebody has swap it with a frankenstien version b4 I got it

[BenHar]

Six cylinder?

Ben

[Corasdad]

Na sadly only 4 or mabay even 3 lol

[BenHar]

Most likely cause is an air leak on the intake side.

Ben

[Corasdad]

Blue sensor changed but still as bad icv cleaned still same

[BenHar]

Most likely cause is an air leak on the intake side.

Ben

[Corasdad]

Looked at the rubber today all looks good I did notice gasket was broken in manifold have ordered a new hope that works