4.7 engine acceleration problem

[dan442]

I have a 97 e150 van with the 4.7 engine. It runs good except when I try to give it more than 1/2 to 3/4 peddle. Then it starts to bog down. It actually picks up speed easier when I don't get my foot all the way in it than it does if I give it too much gas. I just had new plugs put in and they were no help. It's pulling an O2 sensor code(forgot which code) and some other code my tech says could be a vacuum leak. Today I accelerated slowly trying to eventually go to the floor and when I got past about half way it began to bog. Any ideas??
Thanks,
Dan

[G O R T]

Check fuel filter and fuel pressure under load for a start. Insufficient fuel pressure or delivery will kill power and top RPM.