Rough Idle

My 99 Dodge 1500 5.9 idles rough from time to time. its always after school, its not the coldest part of the day its afternoon. It while its in drive also

any ideas?

The best thing would be to bring it to Advance auto and they will scan the codes for free. If codes are present, then it'll point you in the right direction.

Some possible things it could:
plugs/wires
O2 sensor
coil

But you'll need to see if codes are present first so you are not blindly pouring money into it.

try cleaning or replacing the iac.