When this happens, look inside the carb and see if there is a lot of vapor coming out of it. Also feel the carb and see if it is really hot to the touch. If it is boiling the fuel, a 1/2" insulator spacer under the carb may help. I have seen heavily worn timing chains cause this, and also a cam that was installed a bit off (discovered this on my 1st cam swap).
'78 chevy truck-355, 9.4-1, vortec heads, XE268, vortec rpm intake, 750 edelbrock, flowtech headers and terminators.
'77 Nova-slowly progressing project.
'78 Nova-parts car?
'95 Lumina 3.4L DOHC 210hp daily driver