Answer to your question YES.Actualy a EGR valve doesn't reallystart working until you get up to higher speeds. At idel and slowerspeeds it's not active. So if something is wrong with it weatherit be EGR senser bad diaphragm orvacum hose the problem will showupat lower speeds and idle. It actually causes a vacum leak wichyou wouldn't notice at higher RPM's. It cuases your engine to run to lean making it run bad atlower RPM's. Hope this brings some light on this for ya.
Assuming that you aren't over-heating, check the fuel pump. My 1999 Taurus used to stall/ refuse to start when it was hot due to a faulty pump.
A very low idle can cause a 97 Ford Taurus to stall. Another reason for stalling may be transmission bands sticking, which does not allow the transmission to come out of gear on idle.
not downshifting.
It depends on the gearing of the car. If you are in the highest gear and 40mph in that gear is under the idle rpm of that car than you will stall.
put a bigger carb on it.
Not much faster. True helicopters are limited in airspeed. The helicopter blade can not fly faster than the speed of sound or it begins to flutter and even stall. The advancing blade has to go through the air faster than the retreating blade. The speed of the blade is the sum of the speed of the helicopter in forward flight plus(+) the rotational speed of the turning blades. If they can design a blade that will work at slow speeds and at speeds greater than Mach 1, then maybe they can build a faster helicopter.
It sounds like your engine is not getting enough fuel.
Bad head gasket or weak fuel/ spark.
Need to know the year and make, It would help answer.
I'm no mechanic, BUT that happened on my Taurus when the fuel pump was not functioning properly. Best to take it in.
If the engine runs cold you might try replacing the thermostat. I had a similar problem with a Plymouth van, at low rpms, turning corners,,, it would stall.
The first thing I would try would be cleaning the throttle body with some carb and choke cleaner. When they get really dirty it can cause you to stall at slow speeds. On my 93 there is a Crank Shaft Position sensor. Mine started to melt and the jeep stalled at weired times for a week. If your jeep has a lock up solenoid in your tranny and its stuck on, then you will stall at stops Not sure about a 94, but my 2000 would stall while driving at highway speeds. Dealer replaced the oxygen sensor and it fixed the problem.