2000 Blazer Won't Start In Cold

My Blazer dosen't start in cold temps. I've had it to my mechanic several times and he can't find the problem. He has tried many different things (replacing sensors....etc.) But still can't get it to start (in cold weather)...It acts like its not getting any fuel...it does crank...and crank but .......... Now, Funny Thing I Just Figured Out A Way To Get It Started YESTERDAY. It Starts When I Just Barely Turn The Ignition Switch. (Not Turning It All The Way) It Starts In The "running" position. THIS SEEMS TO WORK BUT I'm Sure This Probably Isn't Good For The Car, Plus I Have To Tell My Family Members Ther's A Certain Way To Start The Car....has Anybody Had This Problem?