Another 3.2 Misfiring/Rough Running Question
 

I have 70 911 with an 86 3.2 that has been running perfectly until it wasn't; perfect one day then it bucked like a prize bull at the state fair under acceleration and coughs & spits at idle. I've been following Jacques' thread on his damp weather misfiring issues and tried what was suggested there. Below is what I have tried, and nothing has made any difference. If anyone can think of anything I have missed or if any of the results look wonky, please let me know. I have an appointment next week at a local shop, but I would love to figure this out so I can get back to driving!

Items replaced/swapped/fixed
• Speed sensor replaced with new (existing speed & reference sensors checked ok @ 1k ohms each)
• Coil swapped with new Pertronix (original put back in)
• Motronic swapped with known good unit (original put back in)
• Vacuum line not connected to passenger side fuel pressure regulator (re-connected)

Items checked
• Fuel pressure (35 psi)
• Fuel filter (clean)
• Fuel injectors (open/close & not clogged)
• Cylinder head temp sensor (1.73k ohms @ 88 degrees ambient)
• Distributor cap & rotor (visually checked & cleaned; rotor tested @ 1k ohm)
• Spark plugs checked & cleaned (all 5.4 – 6.2K ohms)
• Spark plug wires ok (all 3.5 – 4K ohms from inside cap thru Beru connector)
• Coil wire ok (1K ohm)
• Water mist plug wire test – no light show
• AFM -smooth voltage rise (.45v to 7v with 9v battery)
o AFM temp sensor is 1.9 K ohms @ 85 degrees ambient
• unplugged each spark plug 1 at a time – no appreciable difference in engine
• Idle control valve removed & cleaned

Compression
1. 166 psi
2. 173 psi
3. 172 psi
4. 166 psi
5. 166 psi
6. 175 psi

Vacuum leak?
Spray some starting fluid around base of intake manifold.
And check idle switch, make sure its closed when throttle is closed.

If you're going to check for a possible vacuum leak, you may want to take the IAC valve out of the loop by jumping the connection first (as you would if adjusting the idle). They can make pretty quick adjustments that may mask any changes in idle that you're looking for if a leak is located.

I previously checked and fixed a disconnected vacuum line and no other leaks are apparent. I also checked the idle switch and it is working properly. I have not done the starter fluid test, but I will pick some up and try that today.

I sprayed the starter fluid into the throttle body while it was "running" and it did nothing. This leads me to believe the issue is ignition related and not fuel related. At least that's something.