even if the CEL is not on or has not illuminated, a code could have been tossed. the code would be in the KAM. if you have a split second malfunction, it could not touch off the light, but pop a code. worth checking, IMHO.
you are losing me: if i read correctly, you said it does not hesitate when revved in park. then you said it does hesitate......
i would check out the TPS as everyone else mentioned. if there were certain situations where the issue did not occur, i might have looked past it. but it sounds like the problem may be there pretty often....checking the TPS takes 5 minutes and voltmeter (analog is preferable).
check for a nice even sweep in the return voltage from idle to WOT. there should be no breaks or drops. voltage range should be ~ <1.0 volts to ~4.5 volts.
good luck.