I have a 2007 Honda Accord 4 cylinder. I just purchased it from offerup. The people before me obviously didn't do enough oil changes. And didn't take care of it as well as I would have. I will add a list of the things I have fixed on the car. I've had multiple check engine lights and have fixed them all. I currently have zero codes. I use a blue driver scan tool and even on a full deep module scan I have zero codes and nothing pops up. But my long and short fuel trims are my short field trims are at 20% and over. I am getting around 17 miles per gallon. I have tried replacing my MAF sensor, I cleaned my EGR valve, replace my PCV valve. And currently still have high fuel trims. What's interesting is that my car did have a code that told me to replace my gas cap. And so I did and the code is gone. So I'm trying to figure out why I still get high field trims, I know that it can be my fuel injectors clogged up, a bad fuel pump or fuel filter, O2 sensors, catalytic. But before I go and just start replacing what else can I check for? The problem is also I didn't notice my fuel trims were high until I replaced all those things. So I don't know what the fuel trims were before replacing any of it. Otherwise I would have been able to know if maybe my MAF sensor is faulty or something like that. Any advice? Currently put fuel injector cleaner into gas tank hoping to see a a little difference in fuel trims so I know it's the injectors and to replace them.

Drives perfectly fine. If i didnt know about the high fuel trims. I wouldnt have any other symptom. 

The list
AC ✅️
Oil change ✅️
Ignition coils ✅️
Spark plugs ✅️
Cleaned Throttle body ✅️
Serpentine belt ✅️
Oil control switch ✅️
Rocker arm oil control switch ✅️
Maf sensor ✅️
Full engine flush ✅️
VVT spool gasket ✅️

replaced pcv valve ✅️ 

Flush Coolant
Trunk
Hubcap
Rear windows