I doubt your problem is the vanos.
It would be useful if you had a code reader and read the codes before they erased themselves. I suspect you would get misfires and lean codes.
Try disconnecting the MAF. See if that resolves the problem. You can clean the MAF with CRC MAF cleaner. Be careful to not damage the wires on the sensor. Slowly spray to coat. Do not power wash.
Are you using an aftermarket engine air filter?
This could be a vacuum leak. When were the CVV and associated hoses last replaced?
Check your air intake boot for cracks or leaks. The small branch to the ICV is susceptible to cracking.
Clean your ICV, but that's no likely the problem.
How old is your fuel filter?
In the morning, start the car and listen under the hook for a whistle.
Hope this helps.