Engine Issues
 

I have an 89 260e with about 140,000miles on it. I've had it for about 3 years now...for the first year I had the car, I drove it everyday. When I went away to school for the first year, it would rarely be driven but whenever I would come home and use the car, it would start and drive just fine. But in the last year or so, I've noticed that whenever it doesn't get used for a week or so, it often has issues with stalling out - it will start fine initially but then after a minute or so the car will shake a little and the engine will stall out. Sometimes it will take a while to get started again and I need to run the engine up at 2000RPM or so for a good 10min before the car will drive and start normally. Once this happens, the car drives absolutely fine (except I've noticed that at idle and in park, from outside the car you can hear a very faint putt-putt-putt-putt type of noise from the exhaust pipe I believe). This summer I've had no problems with it until recently when I didn't drive the car for about 4 days-- it started fine but then stalled out after about 2min and it took roughly 30min of constant attempts (just turning the key in the ignition) before it would start. After 10min or so of revving the engine in park and it was back to normal and for the last week everything has been fine. Just curious if anyone knows what might be causing the car to do this when it sits for a week (or even 4 days). I put in new spark plugs about 10months ago and a new alternator was put in a while ago. Thanks for any help.

Do an italian tune-up!
 

The cheapest thing you can do is buy 1 bottle of techron and put it in 1/2 gas tank. Take it for a long drive in the highway at a "safe" speed to loosen up all the carbon built up. Soon after that, change the oil.
Good luck!