So I bought this mustang a year ago for my gf as a daily driver. It ran fine and I had no issues. Once winter came around the car wouldn’t start after a cold day (I live in Michigan where it was getting to 0 degrees.) so I figured it needed a new battery considering it would start and run after a jump which I then got a battery well above the cold cranking amps this car needed. When it was warm and summery weather the car had no hesiststion starting. Long story short it wasn’t being driven anymore, the weather got colder again and sat for 2 weeks where it had trouble starting, it would start after several attempts, again getting to the point where it needed to be jumped. After moving it into my driveway and after a spirited drive I shut it off and went to start it again after about 15 seconds. It’s ran really rough, low rpms and shaking so I shut it off after 10 seconds of that and it’s hasn’t been started in 6 months. I’ve replaced spark plugs, wires, fuel filter and fuel pump. I replaced the plugs wires and filter and had no issues but still no start, low and behold I was not hearing the fuel pump prime anymore, so I tested for power/voltage to the pump via the connector at the rear of the car above the tank. I Indeed had power but when I checked it, and would turn the key to the on position my dash would read “————“ the radiator fans would turn on and the theft light is flashing rapidly. Leaving the key in for 30 seconds makes the theft light blink much slower. I’ve triple checked all fuses and all relays (even switching them all around with similar amp ones) and still no luck. I’ve read that it seems to be a pcm issue but am having no luck. Any help and suggestions would help, I’ve charged the battery to full and will be cleaning the terminals, checking for power at the fuel pump again and at the pcm. I did read someone saying to hold the trip/reset button down when turning the key to on position, and when I do that the odometer reads “test” and allows me to go through a bunch of options and codes I don’t understand. I’ve also tried resetting the pcm via disconnecting the battery but no luck.