Q: rough idle on start up everytime

2003 BMW 318i 2.0. Car would take 3-4 tries to start up and then immediately stall if i didn't keep the revs consistent and between 1 and 2.5k. There would be loss in power while driving.

Parts changed to try and cure (btw no EML light and nothing on diagnostics):

• EXH and INLT camshaft sensors
• EXH and INLT solenoids
• Timing chain tensioner (old one was 5mm shorter)
• Full service

Timing chain was inspected with rocker cover off - was fine Car has only covered a genuine 58k miles

Rocker cover gasket was replaced about a year and a half ago due to smoke coming out of where the EXH manifold but this problem is still present whenever the car starts up.

All parts are from BMW dealer so this problem has cost me a lot so far.

So after these parts replaced. The car starts up first time but again have to keep revs over 1k otherwise it will stall. After keeping revs consistent and letting the car warm up for 10 minutes. The idling levels normally and then it drives fine with no fault.

My car has 58020 miles.
My car has an automatic transmission.