I met this problem once before, while I start from a traffic light, the car's gas pedal doesn't response to whatever pressure I gave to it. it just like the car lost its power and then died.

It has been a while after last time, the car act well. But today when I start the car(it parked there for two days), I noticed sth different, while I back it out and shift tranny to Drive, it does not response very well, when we come to the first stop it just lost power, I can't speed it up, NO MATTER HOW HARD I PUSH THE GAS PEDAL, THE RPM DOES NOT GO UP!, then after a while the check engine light comes on, and it died.

after waitting for five minutes I restarted it, this time it works fine.

I tried start and switch off a couple of times, it still has the same problem.

where shall I check for? would that be a sign of vacum leak?
or fuel delivery problem?
this car had a new fuel pump back to Jan. this year.

thanx