1988 Pontiac Trans GTA stalls when out on D

Does it need a full servicing? Plugs & wires, cap and rotor, HEI control module, located under the rotor, ect running lean, Fuel filter. tcc solenoid (torque lockup) or neutral safety switch. Low vacuum/low manifold pressure. I would start testing sensors per a repair manual procedures for your car. Some of these cars have issues with burning wires so check them all and the ones from ignition coil to the ignition module wiring. Idle speed to low, vacuum leak, Low fuel pressure, lock-up torque convertor problem (TCC). PCV valve dirty. You can unhook the TCC and try to drive it if it does then solenoid or your wire harness to it needs checked, if it does not then its a engine issue or trans issue. Pull and check all sensor or electrical connections (including spark plug boots) and clean with computer board cleaner (aka contact cleaner) and apply a generous amount of dielectric grease.