Idles as if the engine is going to shut down but does not

[Basha3]

I have a Z3 99 2.8.


I have preformed the following maintanace:

Vanos Seals but not entire solenoid
New CAM sensor
Water Pump
Head casket cover
spark plugs
spark plugs cables
engine seals.
New Temp Sensor
New Thermostat sensor
Fuel Pump
Fuel Filter
New Fuel Injectors
New Fuel Lines.

On the winter days I get this rough idle after few normal idle minutes. It then start to idle as if the engine wants to shut off. then after a few mins is runs normal.

What can be my issue guys?

[328 Power 04]

Have you smoke tested the intake tract for vacuum leaks?


What codes (if any) are stored in the engine computer? Is the CEL on?





FWIW, there are no spark plug cables, and no thermostat sensor.
It sounds like parts have been shotgunned at the car without much diagnosis?

[Basha3]

Installed new intake boot.

Yes there are. What do you call the cables\wires that connect the spark plugs' head to the cover-valve cover? ( Spark-plug cables)
Yes there is a thermostat because the temp gauge was never on normal temp, As soon as I changed the thermostat sensor inside the water-pump, boom the temp gauge kept its level.

- - - Updated - - -

Much diagnosis has been performed. This is pretty much a full rebuilt.

[Basha3]

THE new spark plug cables helped with the hesitation issue I had when I gun it on second gear cornering. That issue is no longer there due to the old cables being cracked at the grip of the spark plug resulting in misfire when turning and engine hesitation.