Carb Doctors inside please!!!

Hey guys, well, i have had a problem here for a little while now. It seems that my car "pops" yes pops. If I am at a steady idle, you here this little whoomp kinda popping that can be several in succession, or one then another in a few moments. It shakes the exhaust system quite a bit when it does this. I am wondering what the hell is going on. Is there something wrong with the fuel mixture that could be casuing it to detonate or something? Its weird. I have always felt that my car is sluggish even for an LG4, but i do not know why its doing this. The car has never really given my any major trouble. But these carbs are very hard to tune and don't stay tuned for long at all. I'm wondering whats going on. Could it be a computer problem? Also, this is weird, but when I disconnect the plug to the mixture control solenoid on top of the carb while the car is idling, the idle smooths out dramatically. It still does this popping, but not quite as frequently. Once I plug it back in, same old SHIITTT. Any help would be great guys, I'm just trying to get some good use out of this motor while im working on getting the tpi 355 ready for install.

Will

Check for a vacuum leak. My nephew had a similar problem pop up on his 87 Z28 and it turned out to be the vacuum line from the carb to the brake booster. It had fallen off in the back. If the default for the carb is rich when you disconnect the solenoid, that would tend to point to a vacuum leak also.

Other possibilities: garbage in carb passage(s) or timing is off.