Major money pit, you could easily spend twice the value of the car and still have issues. Abandon all hope.

My new yorker was a perfect daily driver, but in January one night it shut off after starting, started again but it was fine, perfect the next day, but when I left work everything interior kept flashing/restarting over and over, and the engine starts but shuts off immediately every time, sometimes immediately. Sometimes after a couple seconds. It had a brand new battery, I replaced alternator, terminals and checked all connections, I still can't find the problem. Im sure jts not fuel related becuz all accessories don't function normally now except windows. Is it maybe the PCM or ECM or the computer? Haven't taken it to a mechanic yet! The engine is a v6 i believe 3.5l, it used to be a police interceptor, it has 161,000 miles. Before when the engine was running, with key in, u would have to turn key slightly more in order for A/c and stereo to turn on. Also in the weeks prior to problem, I ran over a car battery left on the highway becuz I couldn't swerve to avoid, idk if it is related to the problem becuz it didn't start immediately. Please help! I live in Portland Oregon and the problem started in winter

I bought the car for 350 and it was a perfect daily driver until this started... I domt wanna give up on it becuz it seems like it should be easy to fix, before this car i had a 1999 toyota camry 272,000 miles and I drove it for like maybe 2 months when the alternator failed on me at same exact time as the hood flung open on the highway, I made it home okay but eventually scrapped the car since it had high miles and previos damage plus all other electrical components stopped working when alternator failed