You are on the right track. Ensure you have the alternator belt tight and are charging 14 volts or so. Also, have a good battery, not marginal, fully charged. On my 88 300E, with a marginal battery, it would start and run if I held the gas for 2000 rpm or so. The ABS light would be on and it would die if I let off the gas. After a period of time it would "click in" with an rpm jump and extinguish the ABS light (OVP relay action ?), and it would be good to go and not die. A new, hot battery and frequent use avoided the condition.