Fuel pump issues

How you doing i'm having a fuel issue with my truck. I have a 2000 ford f-150 4.6L V8 2WD. It has 87,000miles on it. The truck is a custom truck. I had an air ride system put in the truck for shows. The truck was body dropped 4 inches and bagged. So the truck lays out on the ground with frame. So by doing this I had the gas tank relocated to behind the axle. Well come to find out the person who moved the gas tank swapped the gas tank out with a 2000 chevy blazer gas tank. Well as far as I know chevy doesnt make over a V6 engine. Now my fuel gauge doesnt work. No big deal I can deal with out it. But the truck is have running problems. I replaced spark plugs just dropped a new tranny in it with new clutch. When idle the truck runs fine the moment I put my foot to the gas the truck loses power and will jump back and fourth. I replaced the fuel filter ad well. The only thing I can think of is the engine isnt getting the right amount of fuel. I plug a code reader in and it spit 3 codes. One was the engine was running too lean. 2&3 where cylinders 2&3 were missfiring. Could my problem be that the fuel pump isnt pushing the right amount of fuel and if so do you know what PSI a stock ford fuel pump runs at? I plain on putting a 20gallon aluiminum fuel cell in I just need to find an external fuel pump bt I dont know what a stock ford fuel pump runs at to know which one to buy. Any help would be great. Thanks