89 running issues

whats up?A little history first,I have an 89 xj that ran great for 2 trail rides then left me on the 3rd.I drove for 2-3 hours and everything was fine until all of a sudden I couldnt get it to go over 2,000rpms due to it back fireing and spitting and sputtering.the fuel pump was really loud so I replaced it and the fuel filter,which was slammed full of rust.I rode for 4 hours sat. and it ran great untill the end.the pump was quiet in the begining of the day but got louder as the day went on,and then the same symptons came again.I pulled the filter to see if it was full of rust again but it was clean draining out of both ends so I dont know if the fuel is the problem or maybe a sensor.I can put it in neutral and redline it but under a load it want hit 1500 rpms which leads me to believe that the tps is okay or it would not rev in neutral.there is no cat on it so I know that it is not clogged but that is what it acts like.its hard to diag this because it only does it after a couple of hours of riding.could the new pump be bad?its an orileys airtec.im stumped,any opinions would be welcome.thanks