problems with idle

well, its summer and its project car time. Got out the old sbc and tryin' to get it running. Its a '93 305 fuel injected engine, and it starts up fine, but won't idle. The idle will drop really really low, like the engine is going to die, and then it will race back up again, and the start to drop again. If you let it sit for a bit, it will die one of the times the rpms drop, if not the first then the second or third time. I can sometimes keep it running by pulling on the throtle cable and reving it up a little. I replaced the idle control motor this afternoon, and it didn't seem to do anything for the engine at all. Still acts the same way. Any suggestions or help you could offer would be great. I'm new at this whole engine work stuff, but I learn best by hands on so I jumped right in. Thanks in advance.

Tim