Hank Hopkins

My F150 has been misfiring lately. It started after a long drive after pulling off the freeway and it is getting worse day by day. I have ruled out compression (150 psi in all cyl) and spark (tested wires, plugs, coil, battery, etc.).

I use an OBD1 code reader and the only code it throws for a KOER test is 332 - insufficient EGR flow. I have dissected the EGR and cleaned the ports with carb cleaner. I also have verified that the vacuum canister is intact and that all vacuum line connections and electrical connections are secure.

The truck has thrown the code for months, but only recently started misfiring. I have heard that the EGR flow should not be affecting my engine’s performance this much, so I’m led to believe it is something else:
I have reason to believe it is connected to my fuel relay system. The fuel pump is working properly and the fuel filter seems to be getting good flow (although I have not put a number to the flow rate).

Has anyone experienced a similar missing issue without and codes pointing to the issue? Is there anything I may be misconsidering? Where should I start in my diagnosis of the fuel system?

I’ve also heard the catalytic converter could have issues, but that would lead to over-heating of the EGR vacuum lines, and the lines have been looked over and deemed intact and functional.

Thanks everyone.