Delayed injection/power to start car

Hello, I have a Zetec Hatch 2.0L I4 NA Automatic. I have been having this problem for a while. I have to switch my car's electronics on for a few minutes before I can start my engine or it will just keep cranking. The prime in the car takes longer than when I first purchased the car and I have never had this problem with my previous car, a Corolla. A month ago I had a carbon clean and battery recharge done and the car started instantly, had healthy sounding rpm's out of the mechanic, and drove like when I first got it. After a few days it returned to the state of sluggish driving after startup, with rpm's giving a lot less power and at inconsistent times, along with the return of having to have the electronics on for a while before starting up the engine. I have gotten a myriad of possible issues from mechanics from different places with my ECM/ECU not showing any fault codes whatsoever. I feel like I am being ripped off very very hard just because I have not pinpointed the issue and they are charging me out of the mouth for just diagnostics.