I’ve noticed a “stumbling” or a hesitation in my car when I’m cruising or under very light throttle. This occurs in every gear(5spd) but is most noticeable in 2nd-5th gear. When I apply heavier throttle, it goes away. I’m assuming it has something to do with the fuel system. Anybody have any ideas?

Turn the car on. In neutral, slowly press the gas until rpm climbs to 1800 rpm or so. Is it stumbling? Mine did this and it ended up being the EGR valve. I haven't replaced it yet so I just pulled the egr solenoid to egr valve line off the egr valve itself. (you can leave it open). No problems now. Car drives great. When emissions time came around, I plugged the egr vac line back in and she passed.

Its fine revving or in neurtal. It only does it while driving. Could it be the fuel pump if this is the case? I'm clueless.