Problems like this can be due to some obscure fault, but I awlays find it pays to check the easy things first. So, first, I would check the fuel delivery rate.

Remove the hose from the carb, and put the end into a container with a 1 litre mark. Turn on the ignition, and measure the time taken to fill to the mark. You will have to do some calcs to find out how long it should take, based on a good pump (approx 18 gals/hour?). My very approx calc is a litre a minute. Yours will be well short of that if fuel delivery is the problem.

I have seen many posts where guys have found particles clogging the fuel lines and filters. These apparently come from the insides of the tanks. Personally I have had none of these problems on either car, but I did have weak pumps on both cars, and replaced them with high rate pumps. No more problems now.