Engine shaking right after start and then fine

[klebmw]

Hi everyone,
My E70 2008 w/ 140K miles recently shows some issue. When i first start the engine, it's shaking for about 10 seconds and then running smooth. If the engine is running and then I stop and re-start it right away the engine is not shaking. It only happens when you stop engine longer than 15 minutes and restart.
I replaced ignition coil and spark plugs about a year ago and also replaced air filter and clean MAF sensor.
There is no engine check light.

I am thinking about the fuel pump pressure or fuel pump relay issue.

If it's related to fuel pressure issue, what should i replace? fuel pump?

Thank you all!

[Court X3]

Is it throwing any codes or can you pull any?

https://xoutpost.com/bmw-sav-forums/...-start-up.html

Check this thread, #10 response is on point

[klebmw]

Thanks for the input Court X3! Intake valve cleaning is another option via the thread #10.
I will try to remove intake manifold to clean and replace intake gasket as well.

However, today i test the engine: Whenever i insert key knob and turn the ignition on (not start the engine yet) and leave it for 5 seconds and turn on the engine, the jerk/shaking and moving rpm needle up and down disappear -> engine start normal.

It only happens when i insert key knob and turn on the engine right away.

This makes me think about the low fuel pressure due to in-tank fuel pump issue.

How do you think?

[Court X3]

Could be a possibility