I had a bad experience getting parts from Desert valley Autoparts. course it was cylinder heads. 1 was cracked and they switched out to another head that ended up, I found a crack, then they claimed not to have another. ended up paying $80 to ship the $160 part back to them for a refund that they slacked on. I ended up going to a local U pull it and pulling a good 1 for $35 ( was for a 200 I6 Ford so, a little hard to find )...

rough idle, after warming up or all the time?

if it's just after warming up, change the temp sensor. theres a little more troubleshooting if it does it all the time