[VeX]

When you removed the Kleen Air stuff did you leave one of the ports on the fuel tank open? If you close both it'll do what you described when the fuel tank vapor locks. If you had a vacuum leak it would've idled higher normally, not stumbly and stall easily.

 

[VeX]

Exactly. Leave one of the Kleen air holes OPEN. It will vapor lock the tank otherwise. The overflow lets fuel OUT if the tank is over full. It doesn't allow air to come in.