Update: I checked for codes on a hunch and there were two of them: 25 and 52; so I checked the knock sensor to see if it was damaged (it was not) and then unplugged the 15a ECM fuse for a couple minutes. I"ll know in a day or two if those were the issue.

Hi All, I have a 94 4Runner with a 22RE and about 250,000 miles on it. Here's my problem, when the weather gets cold, the mileage drops off. I lose about 20 miles per tank over the winter, it's done this since '08 when I got it, but I've recently noticed a 100 mile difference. The truck runs fine, tuned up about 6 months ago, new timing chain, oil pump, water pump last year, not driving any differently and have same tires, same gas, etc. I'm wondering if a sensor may be the culprit, but no check engine light currently. Any help is much appreciated. Thank you!
PS, I searched the forums (although I'm not an ace at searching) but found nothing related to this problem.