Fuel pressure

Old mechanic, worked on cars that were simple. I am trying to learn the new stuff, I am retired but only one person other than me has worked on any of my car's over 30 some years. I have known many people that have had your same problem from all makes. It is expensive to have a dealership do and hard for the every DIY. I have found that one thing that many over look one thing when nothing else works, when you take the gas tank out, have it have the inside completely cleaned. You wouldn't believe what I have found in gas tanks. And the other problem I have heard of is the seal around the pump. On cars today everything has to be perfect, one bad part, can make another one to go bad, and that is the one that makes your car act up. When something continues to screw up, work your way backwards from the problem you are having, that's when all else fails. Diagnotic's even with today's tech, sometime you have to use the ABC's which a car runs on, air, fuel, spark and exhaust and with today's cars they have to work in unison. But like I said I am an old fart, that usually tell you what was wrong with your car when the car came in, but these were 50's,60's and 70's models and they also gave you room to get at anything without a special tool. But today's cars are complicated, just because the scope say's this the problem, it won't tell you that something else is causing the problem every time.