For the straight connectors, you can get a 1 foot length of each of 7/32" and 9/32" vacuum hoses and cut to length to replace all the straight ones.
Like I said, replace all the straight connectors while you are at it, including those under you airbox at the vacuum cannister. For the "T" connector, call or go to your local Pontiac or GM dealer. I paid about $3.20 for mine. I think somebody said they got one at their local AutoZone or Advance, but the ones near me didn't have them.
Replacing the cracked vacuum connectors on mine completely solved my mis-fire problems.
As mentioned, the 7/32 and 9/32 sizes are what you need, about a foot of each.
Also, have you replaced all the vacuum connector pieces yet? If not, do that and see what you get before moving too far forward, IMO.
And yes, you have to remove the airbox and move the PCM to get to the evap cannister.