Not really sure where to put this, so i guess herel work...

I've got a 91 Firebird Formula with a 305 TPI motor. recently it's started to jump 200-400 RPM randomly going down the road. I'll just be driving, motor will rev up slightly, then drop back down. Any ideas?

 

also, if it's not warmed up, enine speed will go from about 900 down to 300-400 and start to die. And if you have it at an idle and go to take off it hesitates, starts to die, then takes off

IAC?

 

just pulled the iac, theres this "crusty" green residue stuff that came out with it, just a little lighter than the color of antifreeze...