My car has been experiencing the following problems:

1) With a warm engine upon starting, the engine starts but stalls thereafter, unable to maintain proper idling. Engine idles fine on second start.

2) With the auto trans at neutral, when I blip the throttle, the engine does not settle down to a stable idle initially. Idle speed drops close to 200-300 rpm, then stabilises at 750 rpm. It also happens when the transmission is in Drive.

Any idea whats wrong?