850 Carter Thermoquad flooding at low rpm

I am not a mechanic but mechanically minded and looking for an understanding and solution. The car (had it about a year) has a 440 with 460-500hp, Carter 850 carb, with a Mopar Purple cam 296/.557. Overview….. Car fires up and runs nice. I had always noticed after going for a drive it idles rough at stop signs, and couldn’t put my finger on it, but it came to a head yesterday on a long slow drive. I live in rural Nova Scotia Canada and took my wife for a nice long drive along the coast. I probably drove the coast line for 2 hours at 1500rpm 40-45mph. After the first hour I noticed the car getting rougher as we cruised ( the tack would pulse periodically). Temp is solid 180. At the end of the 2nd hour (about 90% of the cruise). I stopped at an intersection it started sputtering badly and it was all I could do to keep the car running. I pointed the car towards home (1+ hrs)….. yep, we are in **** the bed mode. the car kicked and sputtered for the first couple miles and as I picked up the pace it felt a bit better At 2200rpm (once I got it there). The last 1/2 of the drives the car started to feel better. When I got closure to home (and braver) I gave the car a couple of good pulls and every one was better that the one before and when I returned home the car was running normal. I suspect that the fuel supply is too heavy at lower rpm and flooding the car. Looking for thoughts and education. Thanks in advance RonD