1994 Dodge Stealth keeps stalling at idle when warmed up, ..

I have a 1994 Dodge Stealth (base model) with a 3.0 SOHC V6 Mitsubishi
engine and automatic transmission. Recently, my car would often stall when
idling after it's been fully warmed up. It runs fine when it's cold, has no
problem starting up, runs smooth and has plenty of power when cruising or
accelerating, and I have not noticed any drop in gas mileage. But after I've
been driving it for about 10 minutes and the engine's reached it's full
operating temperature, when I come to a stop the engine starts stumbling and
running rough, and the RPMs drop and it stalls out. I thought it might just
be a case of bad watered-down gas, but after 2 tankfuls later from different
gas stations and 4 bottles of Drygas (fuel drying additive) it's still doing
it. It hesitates and stalls even when I slip the transmission into Neutral
or Park. For the time being, I've been able to keep the engine from stalling
by turning up the idle screw, but it still often runs rough at idle so it's
not a permanent fix. Also, my "check engine" light does *not* come on.

Maintenence info: Within the past 20,000 miles, I have replaced the fuel
filter, timing belt, spark plugs, plug cables, distributor cap and rotor,
battery, and just recently the air filter.

Thanks for any tips!



- Logic316