Rough Idle in 2002 Explorer

We recently had our vehicle in to get the water pump pully replaced (it was squealing) and since then the car has been idling a little rough. Is it possible that they tightened the belt too much or is it something else entirely?? I know next to nothing about cars and don't want to get raked over the coals when I take it in to the shop. (i.e. Gee your entire engine is bad, that will be $5000). I want to at least sort of sound like I know what I'm talking about.

The air flow meter went bad on ours at only 16,000 miles but it did not appear to make it run rough, just crappy gas mileage, but if they don't work even a little bit, then that may be the problem. A code should pop up if that is what it is, I thought I was the only one that always had something else happen when I took a vehicle in for repair :banghead:

by iding rough what do you meen?......i find that if i dont let the vehicle warm up (2003 explorer...1500 miles).....the engine can idle or back up with almost a revving sound. .......in other words even tho im putting adeqite and even pressure o the gas it feels like im revving the engine.