I purchased a 2004 350z that had a horrible oil consumption issue. To fix the problem I swapped my old engine 134k mile for another engine with 72k miles.

I also took the opportunity to install brand new stock clutch. The old clutches were exedy clutches and they were in pretty bad shape. My car has apexi catback exhaust system and Cold air intake.

My old engine throttle response felt great. Ever since the engine and clutch swap I feel my car has gotten a lot more sluggish than it was with the old engine that consumed a lot of oil: Any ideas what might be contributing to this? Could it be it that the new engine needs to get Dyno tuned?

 

Have you used your Z's onboard diagnostic system to pull any codes?

 

No I have not, but shouldn't the car have a check engine light or any other light regarding the issue that is detected?

 

CELs are not always an indicator of a code(s) being held in memory. Also, while the VQ replacement you installed has fewer miles than your original VQ, there's no telling how HARD those miles were or what kind of maintenance it received. Could it be that motor is simply in worse shape than you imagined? Did you perform compression and leakdown tests?