The 86 300E is acting funny.
Symptoms
-Had been shifting a little rough (I thought it was a bad front flex disk or differential/transmission mounts or rear suspension).
-Have had some loss of gas mileage (thought it was from running on straight cat until I replaced both mufflers, but it did not get all the way back to 19 or so mpg).
-Today came to a stop after 30min +/- highway run and died. Started back up easy but surged a bit and died a few more times over a few miles.
-I noticed that when it surged and lost power, the manifold vacuum pegged on the economy gage (meaning aprox. none?). After it cooled down a bit it seemed a little better and the stuttering/dying disappeared (over another 2 miles)
Haven’t driven since.

Do I have a vacuum leak?
Where should I start looking?

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13
http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14