Running rough when hot - where to start?

[911kiwi]

Stock 1972 911S 2.4 with MFI. Starts and runs nicely, pulling cleanly thru rev range when cold. Once engine is above 180 degs, engine develops serious miss to extent that it sounds like it's running on 5 cylinders.
I suspect it's an ignition problem - but where to start?
Car has petronix installed which been working perfectly.
New plugs, timing checked. Have new plugs leads, new dist cap so can try these.
Hoping for a short cut solution I guess. What ignition component loads up first when HOT?
One strange (possibly unrelated) ocurrence is that when I do a tight left turn at speed, there's a slight hesitation in engine - as if fuel starvation - have a new fuel filter to install to check this out.

Any suggestions welcome - plan to work by process of elimination today.
Thanks,

[spydr32000]

Have you checked your coil? Also I believe the Pertronix can give some strange problems at times.Check EVERY electrical contact related to the ignition as wellWhile your trying your spares don't forget the rotor button.
Most likely thing will be leads I'd say.

[911kiwi]

Thanks Mike,
Still trying to find "garage time" between looking after the kids. Will report back as soon as I make progress. Thanks for the tips!

[304065]

Try this: disconnect the paper hoses from the MFI thermostat and carefully move them out of the way. Start and run the engine under load until 180 degrees. Does the problem continue?

I would say it's far more likely that your pump is excessively leaning out once the thermostat rod moves.

When you make a high-g left hander the fuel should move to the starboard side of the car. This will tend to move it towards the MFI pump from the outlet in the base of the fuel filter, which shouldn't cause it to lean out. If your mixture is changing under g, it's definitely time for a check of the fuel system, particularly the lines under the car where they exit the tunnel and run to the fuel pump. If they come loose, or the metal clips that hold them to the body have rusted, you might have a line moving too close to the port heat exchanger, which could result in heating the fuel/vapor lock.

Is the fuel pump making the correct 1-2 bar pressure in the loop between the filter console and the MFI pump?

Good luck!

[911kiwi]

Thanks Mike & John for your input - turns out it you were both kinda on the right tracks.
Fuel & ignition.
The fuel filter was clogged & in part contributed to the problems - esp on hard cornering.
But the real culprit was discovered on checking the distributor cap. The left side clamp had worked loose & allowed the cap to tilt - on hard cornering, & how long the car had run was more the case than how hot the car was (these two factors simply coincided!) - over time the cap permanently lodged itself into the tilted position & 1-2 plug leads lost contact.

Car runs great - up to redline with serious urgency & without missinng a beat!

I'm happy again! Thanks!