Engine Mechanical problem
1991 Chevy Caprice V8 Two Wheel Drive Automatic 204119 miles
my 1991 chevy caprice V8 5.0 car seems to cut off when attempting to stop or ride in low RPM's. I have checked the vaccum lines and replaced a bunch of sensors. No codes are showing and the problem occurs after the car has been driven for a few miles. There seems to be no idle while in drive or reverse when the problem occurs
First of all, I'm not sure what you mean by " There's no idle in drive or reverse". If there's no idle, then your car isn't running.
Now, if you've checked and replaced all of the vacuum lines, then you can eliminate that problem. The next step is to check ignition/fuel.
But first, it's never a good idea to replace things until you get lucky and hit the jack-pot. It only cost you money and hardly ever works.
So perform a basic tune up. (Spark plugs/wires, distributor cap/rotor, and fuel filter)
Mostly all hesitation problems are in either the ignition (spark), or fuel (Carburetor, injectors). If a basic tune-up doesn't cure your problems, then you'll have no choice but to take it in for a test drive. (Unless you are a mechanic with good diagnostic skills)
The next things to check is the output of your ignition system, starting with basic timing. Then move to the ignition control module. If this checks out, then move to the fuel pump. If that flows fine, then you check your fuel injectors. (They may be bad or dirty) After you eliminate these two systems as possible causes, this will mean you have a mechanical problem with your engine itself. (It'll need replacing/rebuilding)