97 Deville with multiple codes & hard to start

Greetings all. I'm trying to help a friend that is having problems with his 97 Deville. He tells me it is very hard to start in the morning, has to crank it about 30-45 seconds before it turns over, gas mileage is very poor, runs rough and sometimes makes a small popping sound for a short time. Running a scanner has come up with multiple codes: P0131, P0151, P0171, P0137 and P0300.
Could somebody let me know what the codes are and if anyone has any suggestions it would be greatly appreciated.

Thank you for any help.

Shows lean fuel trims. could be a bad plug. wire coil, also check fuel pressure, bad o2 sensors can aggravate all this, this needs a fuel scan a diagnostic check to point the problems, no quick answer.