hesitates after engine is warm

[josephg15]

so i got my car running after it felt like it was hesitating...the cars runs great for the first 5-10 minutes...i took it on a test drive and it ran great, brought it home and let it idle for like 3minutes, then the idle started jumping from 400-900 rpm, and the car sounds rough like a misfire...any ideas. could it be the IACV, but why does it only do it after 15 minutes...thanks