i recently swapped a 361 in for my old 305 im having a problem that acctually occured with the 305 as well leading me to believe it is somthing other than the motor... But if i run the motor real hard i.e. racing or just comin off a stoplight hard.. the motor cuts out starting right at 4000 rpm in 2nd and continueing through 3rd and 4th gears... does anyone else have this problem and can anyone help me out with it.. Ive got my timing set pretty well the motor will hardly ping unless you really try to make it but im not sure why it cute out and it also seems to be worse in the day time when the motor is running hotter.. thanks

 

Sounds liek a dying fuel pump to me.