I recently switched from a 305 to 350, put all new sensors on it, knock,ESC etc. Sometimes im getting a code 43, i tested everything out and the system itself is good, as far as i can tell. I had my car in the shop to get my oil pan leak fixed and i had my mechanic look at it, he says its either a bad ground(which i checked for) or my car needs a prom update. Im running a 305 chip still, untill i can get money for a cam and a tune, but he says that he looked on the site that mechanics get access to,(not sure the name but i have been on the site myself with a buddy who is a tech at a ford dealership) and he tells me that it says on there, when installing a new knock sensor/esc you need to get a prom update, which is available from chevy for my car, he says since you cant reflash obd-I cars like you could obd-II cars is the reason for an update, he says to wait till i tune the car and it should go away. now, i have never heard of this mentioned in any thread, or in the swap stickey. Has anyone else heard of this?

BTW, the code throws under acceleration sometimes, maybe once a week if that, its more of a nuisance than a problem, i cant feel the car retard timing and the grounds/sensor checks out(its brand new).