1999 Honda Accord Car Stalls when at idle after warmed up

The vehicle has ~ 95K miles. Timing has been replaced @ 90K (ran just fine). All normal maintenance has been done on normal frequency.
After the vehicle warms up it tends to idle very low (~ 750-800 RPM) at idle (in gear or out of gear). Sometimes the rpm will plunge to less than 600 and stall. If one stops abruptly the rpm will plunge momentarily to 600 rpm (expected since brake booster uses vacuum). I can find no vacuum leaks (sprayed carb cleaner on exterior vacuum hoses ==> rpm change if leak). Made slight adjustment on idle adjust and car runs a little better. What could the issue be:
NO MIL codes (ecm sees no sensor failures)
IAC sensor (?)
Fuel Filter (?) Where is fuel filter on this car?
Fuel Pump (capacity or pressure?)
I do not believe it is the problem associated with ignition recall (engine dies but electrical guages indicate normally). Simply looking for most likely cause listed with possible other causes and any trouble shoot info. Parts are so expensive, unlike older cars, that simply guessing and replacing parts is not realistic.