1990 ZR-1 Hesitation when full Power

[frantinoro]

List of replaced parts:
Both fuel pumps
Spark plugs
o2 sensors

Hello,
Been chasing an issue with my new 1990 ZR-1. When I first bought it the full power key did nothing, and I found out I had an intake gasket leak, which filled 2 of the secondaries with coolant. Once that was fixed, I was having a misfire, and found that out to be a hefty sized vacuum leak, and then driving the car got gradually better. According to the PO, coils have been replaced, injectors, plug wires, and the accordion with a solid one.

Now, when in full power mode ONLY, the car vibrates like crazy and noticeably loses power until around 3-4k rpm (I am assuming - the tach is innacurate), and even then, the vibration just minimizes - it still feels like it has more power left. It has a "tune" apparently, I have no information on it, so I ordered a tune from ZR1specialists just for peace of mind. Any suggestions on what to test?
Thanks,
Francesco