This is an update from a previous thread. I have a stock rebuilt 340 with electronic ignition and a harms built Thermoquad. The car starts up and runs mint for about 35-40 minutes after that it does not want to idle. I had it out yesterday and at the thirty minute mark I was in a parking lot and the car was running mint. I was able to stop and go into reverse and start and stop several times with no issues. 5 minutes later on my way home the idle starting getting rough. I limped to my driveway and tried checking a few things. Choke was wide open at this point. I covered the choke with my hand and the car wanted to stall out. (no vacuum leak??). I tried adjusting the mixtures screws a little and it seemed as though they were already in the best spot. The temp gauge is showing a normal operating temp but after fiddling with those few things the car now does not want to idle at all. It will start right back up but seemed as though it was now loading up. When I give it gas it spudders and wants to bog out, some smoke is present in the exhaust and when it does stall, I can see a mist of gas pop up through carb. It did back fire at one point and blew of one of the vacuum caps on my brake booster. I let it cool and took out a few spark plugs, 4 of them looked a little golden brown and the others look good, just metallic with no carbon build up and no excess smell of gas. I let the car sit overnight and this morning it ran the same, perfect for the first 40 minutes, then rougher a rougher until it was just bogging out.

Let me also disclose that I am by no means even a backyard mechanic. I am trying to learn as I go and trying to try a few things before I can get the car to a real mechanic.