Car Bucking

I once had a customer car with a similar problem, accompanied by rising engine temp. I found that the wire stiffener inside the lower radhose was missing. I surmised that as the waterpump impeller rpm went up, that hose would collapse and then the water temp would rise. Then it wouldnt run right, likely due to fuel perkolation. As soon as the rpm came down the hose would relax and all was fine. Took me a while to figure it out.