My car has an idle problem from around 1500- 2000 rpms. when my fan comes on, the motor idles just fine, but when it's not on, the car will again have a rough idle. Another problem i noticed is, right after you release the gas, the cars idle will then drop below the regular idle @ 900 and then be brought back up. This occurs after i rev up a little bit and everytime. What would cause this too happen? What should i look at? IACV and AITV? vacuum hoses? Please help if you can, thanks in advance!