Rebuilt 318 install problem

I have to believe that all the trouble you had getting it running had a negative impact on the cam break in.
I had it running at first and had it run at 2000 rpm for about 20-30 minutes as recommended from the engine shop, for the break in. It progressively got harder to start and the popping out of the carb continued to get worse to the point the engine would not run/idle.