Have a 1966 galaxie 500XL I put a 1972 302 in it
and it's been great to me so far. I recently added a
3in rear lift on the car to stance it out a bit. After I
did that, it wouldn't go over 55-60 mph. I put a new
fuel pump on it, fuel filter and check the line. I
cleaned the carb out took it apart made sure
everything was in order and put it back on. Runs
great up till 55-60 then it starts to sputter and die.
I've also checked for vaccume leaks found none.
Maybe crud in the gas tank now blocks the pick up screen.
It happened the same to me with my 1967 ford LTD. When hits the 60-70 mph mark stutter and die. I've tried replacing the fuel pump, same thing. The tank cap its vented and appears to be venting. When it dies, the fuel filter is empty and start filling up little by little. No idea whats going on, I'm about to bring the tank down and check the pick up to see if is clogged.