ViceCityPerformance

All this started happening after i installed an underdrive pulley along with a fast 102/ nw 102.

Gto is starting weird when warm.
Motor turns over a little slow, might be a hot starter. Had it rebuilt about a year ago

And then a loud crack when it fires up. Kinda like a knock noise. Just one audible one when it fires then its fine.
Plugs and wires are new.

Any ideas?