I had an oil diaphragm failure on my 1980 MGB's Stromberg carb, and it would sputter, but had complete lack of power, replacing it was easy and it fixed the problem, but I don't know if this would apply to you as it seems like the car just can't stay running.

My MG would die when the diaphragm was bad, but it had so little power I had to crawl home.

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon