Intermittent long crank before starting

I have an intermittent problem starting my car. It only happens after it has been sitting for a while (generally overnight) and does not always happen consistently. When the issue does occur, the engine still cranks fine and almost starts (low rpm), sometimes to the point where the starter kicks out and you have to cycle the key again to crank further. Sometimes this is a few extra seconds of cranking before it fires and sometimes it is multiple tries for ten to twenty seconds before it starts. As soon as is does start, it runs perfectly and does not cause an issue again until it has at least sat for an extended period of time. The problem was occurring almost daily and then I took a six hour interstate road trip and had no issues for several days even after it sat for a day. Then the problem slowly started up again. I have tried cycling the key to see if it is low fuel pressure (am I right there's no schrader valve to check on the 2005?) And that appears to do nothing. I have run injector cleaner through, but also does not seem to solve it. I had heard/read/seen somewhere that leaking injectors would be more of an issue on a hot start but do not remember well enough where or how I came to that conclusion to trust it. It seems like if the pump was failing I would have some issue running wide open but it is smooth and powerful. I have had no codes whatsoever. I do have a BlueDriver code reader and fuel pressure is low fifties when running, drops to immediately to high forties when car is shut off and right back up to low fifties when started again. I do not believe this is at the rail, not sure where it is getting the reading from but I think my app says at the rail is not supported on this vehicle. It has been a little while since I checked that. I have not been overly motivated to find the issue since it has never left me stranded and it is hard to diagnose something intermittent. I am getting ready to sell this vehicle and wanted to resolve this issue before I did. What should my approach be? I do not mind doing work myself and would rather not pay a shop a bunch of money right before selling. Thanks!