Not sure if this is the right section, if not pls move thread. But it´s engine related and it´a 455 My new 72 Electra with a 455 starts bucking at around 50 mls per hour and then looses power, no matter how far you push down the gas pedal. Sometimes it bucks at 45, sometimes it goes to 60 and starts bucking then. Kickdown from any speed same thing. Feels like it is not getting any/enough fuel. Yes, tank is still half full. Slow accelaration until like 40-45 mls is fine, but I never got her over 60 mls. Had ignition checked, ignition was good. Had idle and CO checked and re-adjusted (was too lean, now 4%), checked vacuum hoses and corrected vacuum to distributor and some other hoses as per FSM. Air filter is ok. Engine idles at around 600, starting behavior is perfect (was fine before). All those changes made no improvement. Today I replaced the fuel filter and fuel pump (replaced a most likely factory fuel pump with the skid plate on the arm for an aftermarket one without plate). Car ran great up to 70 mls and I already thought "Ok, great, I got it", and she starts bucking again. On the second run she started bucking at around 50. I do think the accelaration up to this speed is a bit better now, but the main problem still exists. Any ideas?