[guru944]

amehl:

The 2 Biggest Issued with the car starting or stalling intermittently.

1.a You should check your engine Ground (impedance) with a digital volt meter set on Ohms. Read Impedance between Batt (-) terminal/ post and Valve cover bolt and or Throttle body. It should read ~0.01 Ohms Thats Normal. Anything higher is NG. Thats some type of open circuit.
1.b With your DVOM set to 20v dc, read across the same places. Voltage should be ~0.001 Volts. anything higher is NG. That is an indication of current flow in a Ground loop (97.8%) or short (rare). Run a 8-10 ga. wire from a upper waterneck Bolt back to the Batt(-) terminal clamp.

2. Big problem, Harness to either Reference sensor or Timing sync Sensor are Damaged, Open or shorted. Best way to verify this is to have someone crank engine with you safely under the hood and wiggle the wires at the neck of connector on these sensors. The Tach needle may jump or the vehicle may start or sound like it wants to start. That's It. You will have to replace these sensor harnesses all the back to the ecu. "Big Job". I will post pics asap. Lindsey Racing and Ian Porsche (Ebay), a few others carry the Pig tail wire Kit for around 100. Which i recommended.

Porsche 944 Turbo 86 to 91 Reference Sensor Crank Position Sensor Harness New | eBay

I found and just did both, last week on an 1987. Both problems. i took my time(4hrs) but it worked great. Car starts like a champ and idle is at 840rpm after cold start (warm).
I will publish pics later tonight. Whew! Sensors were fine....
PM Me if needed. Later...