So I have been slowly and progressively illiminated many possible problems but still end up with the same symptom. I have a recently rebuilt 302, with a 570cfm holley street avenger, stock heads, weiand intake, mild comp cam, and stock ignition system. My problems started when the engine started surging, only noticeable when the car was in neutral and i reved the engine, to about 2,000 rpm. Later the car started stalling and i had to play with the gas to get it to run, now the car wont stay on unless i have my foot on the pedal. Ive done the following things but still havent found the solution:
1. changed the inline and internal fuel filters
2. set the timming to 6 and then advanced it to 8 since the cam is a mild one
3. changed the distributor cap and rotor
4. checked for vacumm leaks around the carb base, and intake, and hoses
5. replaced the PCV valve and hose
6. set the mixture screws to the highest vacumm reading using the full vacumm port
7. Checked the float level on the side holes, and it was were its suppose to be
So now I have removed the carb. and Im debating over rebuilding it, or just buying a new one, of another brand. But I noticed something while I was removing it, and was wondering if its nothing or its a sign that could lead me to whats wrong, I saw that there was some type of brown residue, like when oil gets burned on hot metal, but not actual oil. The attached pictures are that of what I saw.
Ive also been told that a sticking float could be causing this problem, so Ill get back when I tear into the carb. But any other ideas or solutions would be greatly appreciated.