problem with start up.

[LBaptista]

Hey guys, Im not an advance cat in engine work but need some help. I got a 95 z-28, gut cat, freshly built trany and engine(just new bearing seals, nothing expensive.....) but done to the story, I have no problem once the car warms up but when first starting over it seems as if the car is getting to much air. by that i mean its ideling at 400-600 rpms(not stable just going up and down) and if i reverse bring it to say 1000 rpm and let go the gas it kills out b/c rpm drop rappedly down to 300 and will die out. keep it mind its always from a cold start.
from what i have be told.. to believe is the o2 sensor and i need a "dead" sensor? something that says to the computer its working fine b/c the cat is no longer there... but i dono im lost more than ever and tired of reversing and dieing ,starting ,reversing ,dieing.... i need help or im going to shoot my foot soon so i dont have to drive :mad: .... alrighty well if you can or have some personal advice or need more info email (lionelb@hawaii.edu) or post please... ight peace

[ShadyTreeWorks]

its ither the o2 or( run seafoam or replace) or ts ur mass air or throttly postion sensor, some have weird quirks like that when the start to go bad

[J@meson]

well the idle should be 800 + - 50... so if its between 400-600 the idle is off

[SilverSleeper]

your O2s arent used until the car actually warms up from a few minutes of idling. a missing CAT will not cause this issue either. i ran without one for over a year on a stock motor and never had issues.

[Tiffiny]

opti spark