Motor is a 351m and I recently replaced my old carb with a new one. Suppose to be OE from AutoZone. I made adjustments to it and tuned it and it was running like a champ. A 100 mile rode trip and 2 weeks later it's dieing on idle and drive. I hooked up my vacuum gauge after it warmed up and it's reading low. Around 15, and the idles hopping around a bit.
Now I played with the choke and if I hold the choke plate nearly closed, the idle jumps back up and smooths out and I'm pulling 22 on the vacuum gauge. If I leave the choke alone in it's open position, the motor bogs down and wants to die.
Does this mean I'm running lean? Since closing the choke reduces the amount if air, increasing the fuel to air ratio?? Could a vacuum leak cause this?? It was running perfectly earlier with the idle screws turned outward 3 times. I had to turn them further outward, like 5 turns, in order for me to drive it back home.
I know the EGR valve was replaced, but the first one I bought didn't seem to hold vacuum. You could cap the tube off and the valve would still move freely. You could hear the air escaping. Got a second valve and it did the same. Could it be designed like that??
Any advice? I'm new to carburetor adjustments and I need to learn this since I plan on keeping the car. Thanks all in advance