I have a stock 1600 motor with a progressive weber (32/36 DFEV) on it. It's having significant acceleration issue. Any time I accelerate the engine nearly stalls. I've tried rapid accelerations from 1000 RPM to
4000 RPM in 500 RPM increments and experienced the problem, although it's most pronounced the lower the RPM is. The engine has a Bosch 009 distributor. Timing is set for 30 degrees at full advance on the 009.I've rebuilt the carburetor and given it a thorough cleaning, and I've substituted it with another progressive weber that had very little use on it. Same problem, both carbs.
The motor sat for about two years with minimal use. I could have swore two years ago I did not have these severe drivability problems. Prior to that I ran the same carb for about 4 years with no issues that I can recall. I just don't remember it performing like this.
Also, both carbs seem to run well if the choke is stuck mostly closed. Problems only occur with the choke open. I've fiddled with the mixture screw to no effect. I've verified the jetting on both carbs is correct. I've verified the accelerator pumps are throwing a good shot of gas into it. I've checked for vacuum leaks.
I'm a bit stumped as to where to proceed from here. Any tips would be helpful!