Idle Impreza V8 sti 2003

[marcmu]

my problem is when car is cold i start and idle is in 600-700 rpm and i have to push accelerator a few minutes (if not, i go in road and brake and i have to accelerate to not stop) until engine take some temperature and then remains in 850-900 aprox rpm and car go well. If i try to give more idle, then when car is with more temperature idle will be in more than 1000rpm. Any solution?