Car wants to stall at low idle. on 2001 Toyota Camry

I just turned 89000 miles and have maintained the vehicle very well. After it warms up and when i stop or slow down, it wants to stall. If i put it in neutral and rev the engine, then it is ok. I have changed oxygen sensor, air sensor, fuel filter and had it checked by many mechanics even at a Toyota dealership, but nobody can find anything. It has been doing this for about 6 years. Also check engine light comes on from time to time. Changed gas cap also.

by in Weirton, WV on September 01, 2013
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1 answer 6 comments
ANSWER by , September 01, 2013
What code(s) does it have when the C.E.L. comes on?
COMMENT by , September 01, 2013
The code is PO446. Thanks for any help.
COMMENT by , September 01, 2013
Have you noticed any relation of this problem with the amount of gas in the tank , ie when FULL, or dosen't matter? Does it seem to be running rich as in too much fuel to the engine when it acts up, ie black smoke at all from the exhaust? How often does this happen, once in a week or more often?
COMMENT by , September 02, 2013
Strange you should ask that. I noticed that it happens more often when the tank is full. When it gets below half a tank or even a quarter tank, it doesn't seem to do it as much if at all.
COMMENT by , September 02, 2013
Very good possibility it' an EVAP problem. Fuel entering system and intermittently flooding engine. However these problems are often difficult to diagnose, unless acting up when being tested! Not much help i know but may lead mechanic in the right direction, cant hurt it seems.
COMMENT by , September 02, 2013
Thanks for your help. I'll relay that on to my mechanic. The code did say "evap". The first thing he did was change the gas cap. He said with that code, 90% of the time that will solve the problem, but it didn't help. I was also told it could be the "canister" and/or solenoid in the evap system. Never had that checked yet and it could be a little costly.
COMMENT by , September 02, 2013
That's what i was thinking, hope the mechanic can experience the actual problem, that always helps in finding a solution.