iv got a 91 ef with a 91da swap iv had this code shooting at me for some time. iv replaced the fuel pump,regulator.iacv,injectors,o2 sencer, and still getting 43 poping up on ecu.does anybody really have info or a solution to this code its driving me nuts....

 

Have you tried replacing the fuel filter? Just tossing that out there, possibly run some seafoam or injector cleaner through and change the filter?

That's all I can think of, sorry...