engine sometimes fail to start and then runs erratic

[TonyMZUY]

Hi everyone: my 964 Turbo has come up with a problem last week that we still could not resolve here:

One day, afar running perfectly up to half hour before, it failed to start....I keep on trying and finally it started, but it could almost not passed the 4000 rpm, failing all the time, and it stalls a couple of more times when speed was slowed down.
I took it to the mechanic on a truck, they began checking fuel filter, fuel pump, everything was working good, etc., and without doing anything after a day it started normally, and they tested it on the road and run again Ok.

Then today, when I was ready to go and pick it up, without really knowing what have happened it fails to start again..they unplugged a spark plug, and it was working normally. They left it an hour or so, and it started again..???
It's an intermittent fail that is making us crazy, we do not have ways to scan it as no one is using the k-jetronic system anymore...we are going to check the fuel tank to see if there might be an obstruction as it was not running through many months...

What else do we need to start checking?? what do you suggest.??

THANKS FOR ANY IDEA...!!

[964TargaC2]

try replacing the DME relay in the fuse box up front..

[Flying Dutchman]

dme-relay,

otherwise fuelpump relay or fuelpump,

or maybe O2-sensor(s?)

[roofbolter]

flywheel sensor?
My car would run fine, shutoff and not start again until 30-45 minutes later. Before it got to this point, I would be driving and the car would drop out (shutoff) and come back instantly. Good luck

[Raleigh993]

DME was my first guess. Have you checked your ground straps?

Good luck.