Sounds like the old case of a pinched gas line. The gen 1 had a long gas line and more than one person that did carb mods (removed tank) reassembled the bike and pinched the line on the tank base. Sometimes it runs well, other times not. Choke helped each time.
Check the gasoline bend and cut it as needed. Open one carb drain and put the tank on prime. If it flows, you're golden. I'd pretty much bank on this one.
Second, it is possible that after carb assembly, #4 does not have its sealing washer and lesser vacuum is reaching the tank. Verify this by running the bike on Prime.
127.5 mains on a stock can is a bit rich. Is this with a 2" hole in the airbox? That mod assumes a performance can. Just nosey.
Marc/Atlanta
'99 2" mod & K&N
early Holeshot system
135main/35 pilot