Recently bought a used Holley #1850 600cfm carb. I soaked it for two days in carb cleaner, sprayed more carb cleaner and compressed air through all the openings and put a kit in it. I've rebuilt dozens of carbs with good results, but this one is giving me fits. Everything is adjusted per the kit's specs, bolted it on, ran 5 minutes and started flooding out the bowl vent tubes. Pulled the front bowl off, checked the needle and seat, they looked fine, so I blew air through them and put it back together. Same thing. Tore it back down, checked the floats and adjusted them a bit lower, same problem. Put in another needle and seat, tried it again. Ran fine for a few minutes and then started dripping fuel like it had a bad power valve. All these parts were new, but I changed the power valve and it is better, but sometimes starts surging when driving or tries to die at an idle. It's intermittent. Sometimes it runs great. I have a new mechanical fuel pump, but it worked great with the 3310 I had on it, so I can't imagine that being the problem. Holleys are pretty basic, or so I thought. Have I missed something or should I chuck this POS in the closest lake?