My 2000 Honda CRV starts fine but dies if the gas pedal is pressed before it warms up completely. After starting it and then pressing the gas pedal or putting it in gear, it starts to splutter and dies, then is difficult to restart. If allowed to warm up completely it does not have this problem, and runs fine.
I wouldn't be surprised if the car is suffering from poor fuel economy.
The most-probable explanation for the observed symptoms is that the fuel trim is rich to begin with, which is further enriched by the fuel management when the engine is started cold. Pressing the gas pedal makes the fuel trim large enough to cause the engine to sputter and stall.
So what could cause this? There isn't enough information provided to be sure, but checklist of things to inspect would include:
- an under-reading MAF sensor
- a "lazy" pre-cat lambda sensor
- intake-side air leaks
- insufficient fuel pressure
This sounds like an O2 sensor. Search for info on o2 sensor diagnostics & replacement.