The engine control computer should be checked for fault codes. Any stored codes may lead the the cause of your stalling. Some items to look at would be the crankshaft position sensor, the ignition control module, and the powertrain control module.
Replace the control module under the coil pack. My son's 92 Park Avenue did the same thing. This fixed it. If you want to prove it use a heat gun on the module when running, it will probably stall. My 1996 Bonneville seems to have the same module.