I have a 97 Dakota Sport Extended cab with a V6 5 speed and over 100,000 miles. Since about 70,000 miles this truck started to stall intermittently when you push in the clutch and the engine speed gets down under 1,000 RPM. It did this for a short time and then would go back to running right. Next time you push in the clutch, it might stall again. I have seen black smoke come from the exhaust when it stalls making me believe that the mixture is too rich at idle. I am not getting any lights or codes at all.

This is starting to get more frequent and lasts longer. My mechanics don't have a clue why this is happening. Any ideas what might be causing this to happen?

 

Boy, that's a tough one to internet diagnose.
Idle air control valve, leaking injector, sticking exhaust valve.......
Kinda tough, I'd clean the throttle body real good and take a peek at the IAC.