Yes.
No, the fan's load on the electrical system only causes the alternator to kick in (if it isn't already). The alternator will then add a load to the engine, but the idle speed control system compensates for it. It should settle down at 775 ± 50 RPM, quickly.
- Check that the idle speed microswitch is working properly.
Prop the throttle open slightly (steady) enough to disengage the microswitch. Then using a small screwdriver, listen for the RPM to change when you push/release the microswitch. If it does, make sure that the set screw is pressing the switch at idle, especially when you ease off the throttle (sticky linkage). If there is no change, check the microswitch and its wiring to the idle speed ECU with a meter (several threads on that here).
- Feel the idle control valve (or "idle speed motor") to see if it is buzzing at idle.
Wash it out thoroughly.
- If the above doesn't help, borrow an idle speed ECU and swap yours out to eliminate it as the culprit.
- Report back with what you find...
(If you need either, I happen to have an ECU and microswitch up for sale
HERE ;-)