This seems to me to be a fuel pressure problem, and most likely caused by the main fuel pump. However, I'd still like some insight before I throw any money at this. My '88 740 turbo recently began sputtering and choking out under load after our local temps in Wisconsin dropped into the single digits and below. This issue began with a rough idle when the car was first started in cold temps, but has worsened into an all-out misfire and choking out when I get on the throttle too hard and sometimes it's very hard to start and idles very rough for the first few minutes. Also, occasionally the car will sputter out and sometimes die when I try to leave an intersection. In the past I had problems with a poor connection on the main fuel pump under the body of the car and suffered the same type of idle when it failed. My car has a fresh tune-up, so barring the limited chance of a broken spark plug I'm sure this issue is not tune-up related. It's cold as hell here right now, so I don't want to spend any more time than necessary outside poking around at chance solutions, and I'm not in a position to throw any money at this unless I'm certain the expense will resolve my issue. With that said, if anybody has any insight I'd love to hear it.

 

My first solution would be move to Miami, second option is ignition issues from the temp sensor, and third is something simple like the fuel filter or the fuel pickup. Can you check the pressure at the fuel rail?

 

I don't have a fuel pressure tester, so I wouldn't be able to check that. I do feel like it's a fuel starvation issue because it's more load related than throttle position and acts exactly the same as it did when my fuel pump plug failed. I had also considered the intake air temp sensor; is there a quick easy way to test that? Also, and an fyi, I have a recent tune-up and new fuel filter on the car.

 

Did your recent tune-up include a new air filter? That did wonders for my 740 turbo.

 

No, I bought one when I got the car but it didn't need it yet.

 

You can't tell by looking at the air filter. My old one didn't look too bad. Once I put on the new one, all the problems disappeared. Can't say it will work for you, but it is an easy enough task.