misc. issues, 93 s13 coupe

[s13_gearhead]

Okay, so I'm having a bit of a problem with the car I've got right now.. I bought it with an automatic transmission, and something was definitely wrong. The car wouldn't shift out of first gear until almost 6k rpms, and when it did it shifted very hard (obviously), chirped the tires, and wouldn't shift at all out of second. When I let off the gas and applied the brake at stop signs/lights, the rpms would drop down so low the car would die.

So I tore the automatic tranny out and installed a 5spd, I've done the swap a bunch, and it turned out fine. Car shifts and drives fine, but recently it's been doing the same thing as before, when it had the auto tranny in it - rpms will drop down significantly when I clutch in, almost always below 500, and sometimes the car will die. I checked for proper timing, and proper idle, everything seems fine.

Anyone have any ideas on why the car is losing idle when it's clutched in and braking? I cannot figure it out.