I have a 1989 Formula 350. After sitting 2 or 3 days the car is hard to start. Fuel pressure is 40 to 42 psi. Car has new Delco
fuel pump,strainer,and fuel filter. I can remove bellows from throttle body and spray just a little bit of starting fluid in it and it will crank right up. Sometimes after sitting for a couple days it will start up but it stumbles for a few seconds before running smooth.
Car runs great after it is started. Fuel pressure is about 36 running. After shutting engine off injectors hold fuel pressure good for quite a while. No codes, good plugs and ignition components. Any help will be appreciated. Most of the time if I shut car off before entering closed loop it will not start right back up. After entering closed loop it restarts fine.

Thanks
Buck