2003 Mazda Protege fuel system too lean

2003 Mazda Protege 4 cyl Automatic 89000 miles

I have had my Mazda for 5yrs. And I have had no problems at all.
It may be a coincidence but it seems like my trouble started after all of this gas shortage mess started. I wonder if I got some trash or debree from the bottom of the stations tank.
PROBLEM. My cel came on two weeks ago, the diagnostic said system too lean. I used injector cleaner and refueled. At that time the car was showing no problems. A week later it began to stumble during idleing. Then it began to hesitate during acceleration, I have to wait until all traffic is clear to pull out. Yesterday I was sitting at a stop light when it began to jump and stutter like it was trying to stay started then finally shut off. Putting it in neutral seems to help it not stutter when stopped at light. I have had 4 mechanics tell me 6 different problems. I thought I may have picked up some debree and needed a clean fuel filter, but one mech told me my car has no fuel filter. Is built in? Can you please help me? JENN