[G.M.]

You may have sticky valves. Before tearing into thing put a pint of
MMO in the fuel tank. Shake or drive the car a little to mix it with
the gas. While running slowly drizzle MMO down both sides of the
carb. Drive about 30 miles and see how it is. Sticky valve can been
diagnosed by going below 10 MPH in high gear and SLOWLY push
the gas pedal and if it bucks a little it can be sticky valves. When
not sticking the car will pick up smoothly if everything else is in
good order. Take the test before you add the MMO and after. G.M.