What'* up with this? it only happened recently, every time it'* cold, it won't start unless it'* at 100% throttle then it barely runs and I have to keep the pedal all the way down until it smooths out when gets warm after 30 seconds.

I thought it was the MAF sensor, tried it unplugged and even replaced with a new one to no avail. Even Cleaned the IAC and replaced it which I thought may have done something but I still have the problem.

is there a problem with the O2 sensor?
Could there be an unknown vacuum or exhaust leak? I am getting a general misfire P0300 code which comes and goes.... could this have to do with a need of replacing the oil for some reason? idk

what can it be?

the coolant sensors seem good as far as I know, as far as reading correctly and t-stat opens and closes as it should.

I'm out of ideas as to why this isnt running right at startup and only runs when at full throttle for the first maybe 15 seconds then it'* rough for another minute and it is fine and start normal again because it'* warm.

anyone with any thoughts please let me know. Thank u

Seems like you have a couple of cars, which vehicle are we referring to? Monty or Bonny?

I don't know how you are able to start it when the throttle is at 100%. PCM turns the injectors off during cranking when it sees over 85% throttle. This is called, 'clear flood' mode. Next time, just hold the throttle open a little bit and see if it starts any better.

Let'* see if your fuel pressure regulator is dumping fuel and causing hard starts....

What they said, especially the part asking what car.

Also:

Odometer?

Any trauma?

History of the car?

When this happens, are you trying to start with the throttle already at 100%, or attempting to start it, failing, then putting the throttle at 100% ?