Originally posted by R Pope
Going to a stock, low-speed stall converter will make your problem worse. The high stall allows the engine to run at higher RPM without moving the vehicle. I agree that you may have a vacuum leak. Spray WD40 or similar stuff along the intake/head join, if the exhaust smokes or the engine speeds up, you've found the problem. I use ether starting fluid, no mess to clean up, but many are too faint-hearted to try this.

I don't think it has anything to do with you converter.