i have a 97 z28. when im driving on the hwy at about 65-70 mph or whenever the car is under 2K rpm it hesitates and feels like it is congested or something. it takes a couple seconds to get up and then its fine after it gets over like 2200 rpm. the car has a new fuel pump, fuel pressure regulator, fuel filter, plugs and wires and opti.

 

I would double-check everything - that you have spark to all cylinders,
that the regulator is delivering the correct pressure, and check for any
codes.

Has anything been done to the car recently, just before the issue?

 

yea the fuel pressure is showing 45psi. but it is showing a code for the IAC and saying that the car is idling high but it idles right at 900rpm so maybe that IAC sensor needs to be replaced