There are a lot of prior threads here on your problem and how to diagnose it. First, if you have not already done so, read the forum FAQ on how to search here. Then in addition to searching your symptom words, seach for how to test and diagnose the TPS (Throttle Position Sensor, use the words, not the TPS acronym as the search engine here does not work on anything less than 4 characters or letters), IAC, (Idle Air Controller), both are attached to the throttle body, and if you do not have some kind of manual, like Chiltons, or Haynes, go buy one at the local auto parts store for about $17. Eventually you will want an FSM (Factory Service Manual).
The TPS, IAC or the relay that powers it, the IAT (Intake air temperature controller), or even some sticking open fuel injectors can cause your problem.
Sounds like your getting too much fuel and not enough air at start up. The throttle, gas peddle, does not control fuel rate at start up, but does allow more air, so if the TPS and or IAC, or IAT are bad, and causing the computer to inject too much fuel it can flood. If you hold the throttle to the floor, it turns off the fuel and lets it dry out and start if it has been flooded.
Also, you can cycle the ignition on and off, 2 seconds on, 2 senconds off, 3 times, last step leave it on the third time and it will flash a light that is a numeric code for any computer error codes it has stored.
The TPS does wear out, the IAC does get sticky and needs carefull cleaning and oiling...etc. Also, there are some good links to how too's with pictures of some of the sensors in some of the old threads here.