From the symptoms you listed above it sounds like you have an A/F mixture issue that may be the root cause and not the MSD box. I don't know of another CD ignition box compatible with the MSD distributer so you're looking at a significant investment if you decide to change out the MSD distributor for another system. Before changing the distributor I'd do some more troubleshooting. If you simply installed a carb out of the box without any serious attempt at tuning it then I'm even more suspicious you have a mixture problem. Yes you may have experienced an intermittent problem on a solid-state type ignition system but in my experience I usually find them failed hard (no spark) rather than "works sometimes but not always real good" kind of issues. Before spending that hard earned cash on a new ignition system take a systematic approach at troubleshooting the problem. Here are my three most likely things that may cause the rough running and stalling symptoms you described above: #1 incorrect mixture, #2 vacuum leak (causes incorrect mixture), #3 ignition timing. This is where I’d start. I'd take them in reverse order as the last two are easy to determine and you can check them off your list quickly. Once #2 & #3 are squared away, for the A/F mixture tuning you will concentrate on the idle circuit of the carb -- main jets, power valves (unless you're above 7,000' MSL then I might not discount this one yet), accelerator pumps, and squirters are not causing this issue. First check the float level to ensure it's correct. If you find it high you need to also ensure you have the correct fuel pressure for that carb. Regarding float level, high=rich & low=lean. Both rich and lean mixtures will cause rough running and it doesn't have to be real lean to stall at idle or just above especially with less timing lead. With the floats adjusted you need to set the idle mixture screws to get best idle quality or if you have an O2 sensor, to get the proper A/F mixture. If not constrained by emissions standards I shoot for ~13.0:1 to 13.5:1 A/F at idle and a bit richer just above idle with no load on the engine. For best idle you can trim the screws one at a time until you see a loss of RPM and then open them ½-turn or so and you'll be close but using an A/F meter and vacuum gauge is much more accurate. If you can't get the idle mixture adjusted right and you have idle feed restrictors (common on high end carbs like QuickFuel) you may need to change these up or down in size before you can trim the idle mixture and an O2 meter will tell you quickly which way to go. I like to use a tach, vacuum gauge, and O2 sensor when tuning carbs. It is much more accurate than the braille method (feel and sound) but in a pinch you can get real close without the fancy tools.