Engine Stuttering

[Fi-Alero]

Hey guys,
Ever since I boosted my car, I've been having an engine problem that is annoying me.
I'm going to try to describe it the best way I can lol:
Whenever I'm cruising at ~55mph and trying to normally accelerate to 60, my engine will stutter horribly. I've tried everything I can think of to fix it. At first I thought maybe it was running lean, but my wideband gauge is reading 13arf and according to my HPTuners AFE table, it is less than 1% off designated AFR.

The only way I can stop it from stuttering is by letting off the gas for a second (making me get into a different gear) and then make the car quickly accelerate to 60. It isn't a random thing. In fact, it does it every time. I can tell exactly when the car is about to stutter because the exhaust gets really low (only way I can explain it lol.)

What could be causing this? It is extremely annoying because I cruise at 55-60 everyday for 60 miles.

Thanks for any input.