When you set the timing did you unplug the electronic advance wire?

That would be the coolant temp sensor , located beside thermostat housing.
Clean those grounds in that are while your at it.

Have you checked your fuel pressure? How old is the air filter? And fuel filter?

Maybe the throttle body could be leaking causing the hissing? A vacum leak will cause bad hesitation on acceleration on the low end.

This is true :)

The hissing is starving for fuel , more air than fuel.

This is what I'm thinking it definitely sounds related to the TBI. Possibly an injector leaking? (bad o ring?) I haven't checked the fuel pressure but the air and fuel filter are brand new. I will also clean the temp sensor terminals.

Shamrock, I did not unplug the advance wire when i set the timing.

Also, I've noticed the RPM'S dropped at idle and sit at about 800 now

Shamrock knows those TBI set ups pretty good. I have heard them leak from the flaps or base, I cant remember.

The injectors have a sort of "spattery sound to them and almost like a constant clicking, like a diesel motor. Is this normal?

yes that is normal the click is the injector opening and closing and the other sound is the fuel spraying out......sound like they are working but I would run some cleaner through just because. never hurts to be safe and clean them