98 Continental P0190

Heres my problem, its been bucking and losing power especially on hills. On the flat interstate, I can reach high speeds as long as I don't punch it a try to engage the passing gear. on hills starting out at a stop on a half mile hill I can only get to maybe 25mph and that's letting up on the gas sometimes when it feels like its bogging down. I changed the fuel cap no difference, changed the fuel filter which was the original btw and had a huge difference I thought I fixed it but within a week back to the same. Rented a pressure tester with ignition on engine off i had 10 psi running I had 20 psi, Is it my fuel pressure sensor or my fuel pump? or something else? I'm stumped and about to throw parts at it just wish they weren't expensive probably mistakes. thanks in advance