Start the motor and let the idle settle, then pull the engine oil dipstick and listen for two things, then idle change and a slurping noise from within the dipstick tube. If you get both of these you may have a faulty OSV which is mounted at the rear of the intake manifold. Not sure if that will be the cause of the problem, but its a starting point.
The other issue could be a failing Air Mass Sensor, this is really easy to test, simply go for a drive get a feel for the problem, then turn the engine off, pull the lead off the AMS and go for a comparison run to see if the problem is the same, by default the engine power will be down, but you might notice if the hesitation issue is still there or not.
Good luck and let us know what you find out.