So, here is the deal. I have own a 01 Catera and absolutely love my car. The problem is, the gas mileage has dropped off the map, on cold days the car will only stayed cranked when I give it gas and sustain at least 3,000 rpm. I have had past problems with a few vacuum line hoses coming loss, but that has all been fixed. The car has seen about a 20% loss of power. One thing I have noticed, is the problem gets much worse on cold days, and on hot days the car almost drives like normal. I have a feeling some laws of thermodynamics are in play here. Unfortunately I don't have the time or patience to continue trying to track down the problem. Also, as stated before, all major hoses have been replaced. That is not the problem.