Fuel pressure. 97 grand marquis.

You've done everything, assuming the pickup screen in the tank is clean, on the pump. Get a new gas cap. Try running it with just a rag in place of the cap. Maybe air can't get into the tank.

Also, replace the fuel pump relay, under hood. They go bad.

Well it runs when you cruise around. No issue 100mph. But as soon as you punch it it just boggs out an low fuel pressure

I still say replace that fuel pump relay.

I've got it. Replace or clean the MAF sensor by the air cleaner. Happened to me once, almost got rear-ended. You can buy spray cleaner and tamper-proff bit set at the auto store, or get an exchange unit for around $100.

Can a maf make the fuel pressure drop to 5psi?

Probably not, it regulates how much fuel is injected. How do you measure pressure while driving? I still say replace that relay and gas cap. Either one could do it, and they are cheap. The only stuff I could find on google is for turbocharged engines.