I’m having a vibration issue from 2,000 to 2,500 rpms 89 iroc lt1 swap with a wct5. The vibration is amplified when the ac is running to the point it’s undriveable. It doesn’t matter what gear I’m in just at that rpm range. Runs great outside of that range. Already replaced the ac compressor, new clutch, flywheel, tranny was rebuilt, put a new harmonic balancer, belt tensioner, balanced the driveshaft. In the air I can’t see and feel the vibration coming from the rubber boot area on the clutch. Anyone else experienced this or any ideas? I’ve had it at 4 different shops and nobody can figure it out