First, I want to thank everyone for all their posts - this thread has been a life saver! I too have a similar problem - I just took possession of a '67 Amazon Wagon 6 months ago and it has never run right. It's modified, Weber 38 dgas, and was hard to keep running. Once hot and turned off, very sluggish once started up again. Today, I finally got a complete tank of gas in the car and two blocks from the gas station the car cuts out entirely - no way to get it started again. Waited and it started, but didn't run for long. I thought the gas line was maybe sitting on the block and valve cover and maybe causing vapor lock. This was what drew my attention to the forward gas filter - it was bubbling air, lots of air actually. I hadn't remembered what that meant at the time and only when I read this thread did it click. I went down and took the gas cap off (it didn't noticeably break seal) but when I tried starting the car it started right up and without using the gas peddle - got car hot again and after doing this for 1/2 hour w/cap off everything was fine. Also, zero air bubbles seen in the gas filter.
I'm yet to locate the breather hose off the gas fill intake pipe, but I have every confidence when I do I'll find it clogged. In the meantime, I'm putting an older gas cap on it (I can make non air tight by taking one of the seals off) - kind of a stop gap till I can confirm and fix the clogged breather line.
I too am dumbfounded - the prior owner had this car for years and years - how in the... I too won't go there till I know this is fixed.
Anyway, thanks for the great help. Sheesh, air bubbles in the filter.. how great is that
Maria