go to the junk yard and look for a 91 ford taurus/mercury sable with a 3.8l V6 and take the fan off that. It is a 2 speed fan, low speed pushes about 2200CFM and high speed is about 3800-4000CFM.
I picked up mine from a junk yard for $30, all i had to do was pull it out myself.
I have mine set up with a flexa-lite adjustable switch which turns on the fan when the temp reaches about 195F, it is on for about 15-20 secs then turns off again untill the temp rises back up. So far it works flawlessly when idling and reving.
If you get one, it has to be form a 3.8L V6 not the 3.0L V6 models... it will say on the vavle cover
You can buy the temp switch at Performance improvements for 50 bucks. Its a simple device, you stuff it into your upper rad hose and when the temp reaches your set point it triggers a switch that turns your fans on.