for the "pop", suggest checking the health of your suspension components- closely../brake hardware/ exhaust system hangers/ trans mounts/ motor mounts>>something in these systems may be worn or loose

"lag" culprit may be related to the above or be: transmission/ driveline related, or suspension related = weight transfer causing the suspension to abnormally shift (worn bushings, etc.)

good luck & let us know what turns up.
-fad