Problems With My 1988 Mercedes 260E

[Sh33rc0ld]

I have a 1988 Mercedes benz 260e straight six that just recently will start up and run for about 30 seconds or so until it sputters and dies, or just dies out after runnig for a couple seconds. it does this even when you give it gas. it started doing this about 2 days ago and never did anything like this before. it started while i was on the highway doing about 65. then the car started sputtering and decreased to about 40 mph. so i tried to come back to the normal speed but the car just sounded like it was in neutral and would not go any faster. so i tried to maintain the 40 mph but the car died out and i coasted to the side of the road. it started right back up and managed to get it off the highway and home but the car would only go about 25 mph. any faster and it would sputter and die or just die. and if you came to a complete stop it would just die. i got it home and changed one of the fuel pumps due to loud noises it was making and now the car will just start and sputter and die or just die.