I have a 86 z28 and am getting codes 23 and 45. what i want to know is that if I change the carb out which should I use I have and older qudrajet with no electrical controls or a singal feed 600 cfm holley. but in order to use the holley I'll have to change out the intake also becuase there a re not enough vacuum ports on it which is not a problem because I have a torker or a x-clerator to use with it. hood is not cut for the x-celerator. I think part of the problem comes from the smog pump not being hoked up.but I didnot have any of these problems until I cleaned all the carbon off the bottom of my carb and gave the engine a tune up because the guy I bought it from still had all the orginal parts still on it.