any had this problem w/ an IAC....

i finnaly got around to changing my IAC.....i went and got one from auto zone for a 1995 cobra....i noticed a few differences between the stock one on my carand the new one....for instance the color, mine was black and the new one was chrome...the inside where the air goes, the new one is smaller then my old one......but i know that over the years they change the appearance on things.....so i put it on, reset my computer, and started it up...it was revving to high (2500 rpm)....so i times it down from the distributor...i got it to idle at 900rpm...but when i got in the car to back up i had power(thinking damn), but when i put it in 1st to pull up it nearly stalled from no power...i was like dammit now what...upon further review i noticed it looked more like a fox body IAC...so i was thinking maybe they mixed the IAC's up....so i put my old one back on and went up to auto zone this morning on my way to work....when i returned it i explained my theory...after looking at another for my car they were the exact same....????
so after i got to work i called o'reilly's, napa, and pep boys...the only one with the matching ford numbers to the IAC was a local dealer....and they want 2 times what autozone wanted...any ideas....???? i'm still using my old one until i can get another one....