Toyota Repair: RPM low (at 0), car doesnt turn on, toyota camry 2002, air intake hose

Question
QUESTION: Hi, i have a toyota camry 2002 with 154k miles. the last couple of days the car was taking a little longer than usual to crank up but it will turn on. i was thinking the battery is going bad. after 3 days, i went to the store and when i went to turn on the car it will not crank at all. i thought it was the battery. i boosted it but will not turn on at all. then i press the accelerator while boosting and it turned on right away. when i left the accelerator pedal go, it turned off. so i tried and again and as long as i keep the rpm a little lower than 1000, the car will stay on.

i noticed that usually the RPM stayed below 1000 (when car is off) before the problem happen which is normal. now when i go to my car the RPM is at 0 which make me believe some type of sensor is bad. so i tried the following to make sure they work find.

1. i tried with a good working battery and car turns on the first time. i turned it off and no start.
i press accelator pedal and works fine as long as i keep it above 0. if i take the foot off the
foot of the pedal, it goes back to 0 which is not normal

2. i disconnect the battery and let the car run on the alternator and it stayed on while pressing the pedal.

3. it cannot be the starter, cars turn on when i press the pedal on the good working battery my friend lend me.

so the only thing is that there is something that is letting dropping the rpm to 0 and that is not letting the car turn on. rmp should be slightly below 1000 when car is off. i dont think it is normal if it drops to 0. any ideas out there of what could be the problem? thanks a lot

ANSWER: Here is what you will need to try doing first: Remove the large rubber air intake hose from the intake(throttle body) block the throttle plate open and use a can of air intake spray cleaner and a small brush, both available at the autoparts store, then clean out the carbon black deposits out of the throttle body. Put the hose back on, start the car depressing the pedal all the way down, you need to get a lot of air in, when it starts release the pedal to keep the engine from over revving but keep the rpm up above 2000 rpm for a few seconds then release the pedal, the engine should idle normally, if it idles too low or too fast disconnect the battery negative terminal and reconnect it and go drive it for about 15 minutes, the idle will return to normal at about 800 rpm.

---------- FOLLOW-UP ----------

QUESTION: thank you for your help. it works.  i cleaned the throttle body and it is working fine now.  thanks a lot.  i have a couple of questions to ask you.

1.  how often (miles or year) should i clean the throttle body
2.  how do i test a alternator and starter.  for example, if one day my car is not turning on and the battery looks ok, how do i know is the alternator or starter.  how do i test that?

Answer
Clean the throttle body evey 30,000 miles. Test the battery with a volt meter, it should have at least 12.5 volts, with the engine running it should be 13.8 volts to 14.5v this means the alternator is working, a malfunctioning starter will usually just make a single clicking noise when the key is turned to start.