[V8] Cold killing gas mileage

[QuickAudi at aol.com]

Well, I'm kinda stumped.  At 60 degrees, I can get well into the low 20s for gas mileage, up to 23.  When it is 20 degrees, like lately, up to about 45 or so, my gas mileage barely pushes 18-19.  What gives?  The air temp sensor "looks" ok, MAF is original, and OXS (3 wire) was replaced earlier in the year.  Those were my three guesses.  Also have replaced G82/83 temp sensors and the one on the back of the passenger side cylinder head.
Oh yeah: MERRY CHRISTMAS!!!

Joel
'90 V8q
'86 5kcstq