Check on the engine coolant temp. If this is not reading right, it will cause problems as the engine heats up.

I have not found any solutions yet. It is springtime here so I will not be able to see if problem still exist until weather gets warmer.

Thanks, he said the car temperature runs fine...its just strange that it runs fine on his trip to 45mile drive to work in the mornings...but on the way home when its hot outside the car will barely move. He'* replaced the mass flow air sensor and the catalytic convertor...his next plan is changing the fuel filter...Thanks for any info / advice.

Any codes showing up? Heat related has me think electrical. Like a bad coil.

My 1995 Bonneville would die out on extremely hot days. It would not stall but would not accelerate, it would go at low RPM'* and buck a little bit. It acted like it was not getting gas but fuel pressure checked out fine and the temperature gauge was a little high but the Supercharged engine always runs a little hot unless cruising on highway. I has told by a garage person that something in the catalytic converter could expand on extremely hot days and restrict flow.
Although if I would let the car cool down then it would run OK until the engine temp got hot again, but this would only happen on 90+ degree days

If you have a heat gun, you can heat up the coils. If the engine starts to stumble, then you have a bad coil. They are good at working when cold, then acting up when hot.

agree with dan, wouldnt a cam or crank pos sensor be a likely suspect too for heat soak on a 95