Bogging down at higher speed

[steplift20]

150 1988 Mercury outboard, I was going out Sunday and my boat ran great for about five minutes than at higher RPMs it bogged down, I fuel up at a gas station that closed up after I fueled up, but might have sucked up crap , maybe, so I changed the water seperator and no water that I could see than I changed the inline fuel filter there was black stuff in it but not to much but not a little too, on the in line fuel filter one end is flared out, does that flared end facing the bottom of the motor or does it point toward the top? Thanks