1.9 head job

I just replaced the head on a 94 1.9L . It starts just fine except the engine will race to about 2k rpm then idle to an almost stall and then rev back up and then idle way down again. It keeps doing this cycle until the engine gets warm and then it will idle just fine. Any body have any ideas what I might have done wrong, or what else might be wrong?? I replaced the head due to an overheat problem which cracked it. Please e-mail me if you have any ideas !! Thanks Guys !!
Randy
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Vacuum Leak...you either broke or forgot to reconnect a vacuum line somewhere.

Idle Air Control valve on top of you throttle bdy.