Opening the air meter flap 'tells' the fuel distriibutor there is a higher fuel demand, so it flows more fuel to the injectors. I.e., mixture is too lean to start with the flap in idle position. There is an offset adjustment for the flap, so check and make sure that is correct.

Could be your cold-start or rotary idle valve are not functioning, or you have ruptured a hose somewher in the idle air circuit.

Steve

__________________
'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7