We charged the battery and after putting it back, it won't start due to the message about the anti theft device. Help!

My car has around 170k miles on it and I came home from work one night and parked and when I got up the next morning I had a puddle of oil under the front of my car and I even had oil that ran all along the exhaust. After sitting it quit leaking. I change the filter and there wasn't a double gasket, added more oil and it ran fine for a while and then started leaking again. It doesn't leak when it's shut off. It only leaks after running. Any ideas? I can't really see where the oil is coming from but it's somewhere the front passenger side.

Transmission hangs in neutral, then jumps into gear, particularly when cold or when shifting quickly from reverse to forward. Fluid appears clean and levels ok. This has been a long term thing for a few years.

Engine runs relatively smoothly once at speed. I thought it was fuel flow (eg filter issue), but learned there is no regular filter to service. There should be no excessive sediment in gas tank that would cause that filter screen to block. I'm thinking fuel pump? There is also some hesitation starting..It will not start without applying the gas pedal. Without pedal it stalls out. Thanks

My car won't start and I am getting the P404 error code. It's cold here now so issues are starting to arise with my vehicle. I just replaced the MAF sensor because that was also causing my car not to start just a couple days before this. The other day, I was warming up the vehicle, it was running for five minutes and then it just died and wouldn't start up again. It died but the headlights and internal electric were still on. The day before I was driving & when I was decelerating from a high speed my car "glitched". It's internal electric just sort went off for only a moment, but it was still noticeable and concerning. Also, the voltage (not sure if that's the right word for it) on the battery is higher than it should be. It's at 15 when it should be around 14 I believe. Any suggestions on whether the larger issue might actually primarily be this code or whether it's other issues not found with a check engine light?

The guy did a diagnosis and told .e he could not determine if its a blown gasket unless he takes the top of engine apart and charged me 500 to do so.. Did he cheat me??