car will die when i press in clutch

some times i will be driving and push in the clutch and my car will just die. A Ford mechanic sayed that it was the iac which i have previously clean, he also said that it wouldn't help that much to clean it. So i got a new one and it still dies, although the trottle response seems to be quicker. I don't know if it should have affected the trottle response or not. I recently removed my smog pump and charcol canister but i don't see how that would affect it. I is starting to make me mad so if any one could help i would appreciate it.