Causes for poor gas mileage?

[blind34_1]

Well I bought another car to add to my fleet, but it's getting a little less fuel economy than I expected. (Its a 93 celica GT)

I'm trying to think of all possible causes for bad gas mileage, here's what I have so far:

dirty air filter
clogged pcv valve
a lead foot


not a very good list, i know, thats why I'm asking for input. The last item there I'm working on, I'm just so used to putting foot to floor after driving that escort that its hard to change.

and also I've heard that a cold sir intake could help fuel efficiency by a small bit. True or no? Sounds like BS to me, more air, more fuel, you know?