tuning for ls1 hot cam

I recently installed the ls1 hot cam in my 98 Z28. The service engine soon light comes and goes. I have access to a Tech 2 and it shows a P0300 misfire code with no specific cylinder. Also on the misfire graph it shows a misfire on every cylinder at idle...but when you rev it up a lot or a little it has no misfires. I suspect that I need custom tuning but I do not want to spend $500 for it. Does anyone know if I can use Tech 2 to program my pcm. The car runs great but I would like to not have the light come on. Thanks.