Just bought a 67 Mercury Cougar XR7 289 V8 motor. I test drove it a couple times no issues. Sound great looks great. I pick it up and am on the interstate for 20 miles 60-70 mph no issues. I come up to traffic and am coasting a little at 20 or so mph and it stalls. Starts right back up and I'm good until I get off the freeway and when I come to a stop light and try to go again it stalls again. I get it to my buddies house check it out a little, call some friends (I'm not a car guy by any means). The fuel filter was pretty dirty so I changed it and used sea foam in the fuel tank. Next morning leave his house for home. Same scenario freeway it's fine all the way in. I get off the freeway and it's even fine for a few lights then it starts doing it again. Anytime I stop for more than a second or two it stalls. Always starts back up fine. New fuel filter is still completely clean so I don't think it sucked up any more sludge. I don't really know where to go from here. It was idling at about 600rpm. I adjusted that to 800 and it seems to make it a little worse or the same at best. I went to a shop down the street and they think the carb just needs adjusted but they can't check it out until Monday. Just want some more opinions before then.??