I have a 91 pickup with the V6, in a hunting truck that I just purchased and only use on weekends. It will run for hours just perfectly, if you go down a very rough road with puddles in it, it will start running like garbage. You can shut the motor off and turn it back on and will idle fine, but needs to be feathered to get it over 1000 rpm's once above 2000 rpm's runs fine again, but it is a manual transmission so you can about imagine the struggle. So far I have changed the fuel filters on it twice. The first one was absolutely full without a doubt, brown muddy gunk was coming out and there were chunks that fell out when tapping it on the flatbed. Put a new one on and ran fine. Happened again, changed fuel filter didn't run well. If I limp it home at 25 miles an hour and let it sit the next morning it runs fine until you hit another pothole.
I have taken sending unit off, siphoned tank, and vacuumed chunks out but for the most part was pretty clean. I replaced the sock on the end of the fuel pump while I was in there as well. I believe it is a cobble job fuel sending unit off of another pickup because it is a 2 line sending unit, vs the 3 that the internet shows it should have. It also has just an inline fuel filter not the actual toyota threaded type like its supposed to have.
What should I try next?