04 Mountaineer not cranking. New starter, battery, and ignition switch.

[Locket]

Hey all! I have a 2004 mountaineer that started having starting issues a couple months ago. It would every so often not crank when the key was turned to start. However when it does start it runs great. I replaced the starter first thinking that was the issue, but a few starts in it did nothing again. So I went for the ignition switch, easy enough job, but it still intermittently won’t crank. Well this morning I went to go start it and it appears my girlfriend left the seat heater on and killed the battery. I just got a new one and the truck came right to life! I went to the gas station and filled her up and that’s where she died and got towed home from. She refuses to start now and I’m at a loss. Could this be an anti theft thing since I replaced the battery? Any help would be greatly appreciated, thanks in advance, Tom.
Btw I forgot to mention that it’s also 20 degrees here in Connecticut if temperatures could be a factor.

 

[Tshaw88]

have u checked all of the grounds?? could be one thats not funky from rust build up.