You're idling fast enough to exceed the stall speed of the torque converter, probably. Either slow the idle speed down, if you can, or bite the bullet and get a torque converter that will accomodate the raised idle. "There's no free lunch" where camshafts are concerned. If the engine can't idle below 1,500 RPM, better use a standard transmission, or limit the engine's use to a race track.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!