The engine will not accelerate past idle?

1992 Pontiac Bonneville SSEI 3.8 supercharged mileage: 104,000. Symptoms only occur when high ambient temperature (above 90 degrees). After driving for a while, especially on the highway, I experience the following symptoms 1. Engine will idle fine, 2. Car will not accelerate past idle and will occasionally stall when trying to accelerate, 3. Has OBDI but no check engine light comes on, 4. Have replaced fuel filter, 5. If it occurs while moving you can retain speed at partial throttle but acceleration causes stumbling and feeling of lost fuel pressure.