Vehicle has a good hesitation between 1500 and 2000 rpms only. Otherwise, runs fine. Fuel filter, spark plugs, air filter have been changed. Vehicle has only 40,000 miles on it. Any suggestions for this repair would be highly appreciated.

check mass air flow sensor, and trans fluid

Wouldn't mass air flow sensor throw a code? Why would this cause it at only these rpms, wouldn't it happen constantly? As for transmission fluid - fluid is full - why would fluid do it as these rpms only anyway?

check for corrosion on the terminals on the coil pack, or the wires may be bad.