Celica Start Up Issues

[Jmac000]

Help

I have a 2000 model Celica. When i start my car after it has been parked for several hours and the engine is therfor cool i have problems. I live in a hot climate in QLD, Australia and it seems that my problems are worse in the summer. When i start the car in the summer the car runs VERY poorly for at least 3-4 minutes, when i hit the accelerator the rev dial actually dips before revving up, also it feels as if someone is holding the car back. In the cooler months you can tell that the automatic choke is functioning and the problem goes away.

I am wondering if the automatic choke is coming on even in the summer months causing the problem, has anyone heard of this before or does anyone have any idea what else it could be?

Thanks in advance