rought idle after using a/c

[VinceSez]

Whenever I drive after having used the a/c, my idle will bounce randomly from 650-850rpms (sometimes lower). The car sounds like it has cams at idle, and sometimes black smoke is present at idle. I cleaned the mafs, and also cleaned the iacv through the vaccuum hose on the intake and it helped until I used my a/c. The problem doesn't occur when the a/c is on, it only occurs after i turn the a/c off, or after i turn the car off, and then drive off with the a/c off. Also whenever I drive off it sounds like my car pops/backfires every time my car changes gears (auto). Usually when I clean the mafs and iacv, it clears everything up until i use the a/c. Anyone know what could be causing this problem?

[480sx]

Sounds like your FCID valve has taken a crap. Check your FSM, its the valve that bumps up the idle when the AC on.