One more tech question
 

My 81 928 is still idling a bit rough. So far I have replaced all of the vacuum lines, all new Bosch platinum plugs, a new K&N air filter, new air pump filter, and ran a bottle of Lucas injector cleaner through it. Any ideas on why it would idle so rough?

Thanks

DON'T use platinum plugs, the early cars don't like them that well. Pull the dist cap and look it over as well as the rotor. Have you checked the timing?

Thank for the info!!! I didn't know that they didn't like Platinum plugs. What do you suggest? As far a timing, can it be adjusted with a simple timing light and a distributor adjustment?

Bosh copper or NGK work well for me. Yes a timing light is all you need to set the timing, and a 13mm socket or 6mm allen.

x2 on the Bosch copper plugs (if you can find them).

Timing for '81 US spec cars is 23 degrees BTDC with the vac hose pulled and plugged at 3000 RPM, which should give you 8 to 10 degrees BTDC at idle (750 RPM).

I tune my own car a few degrees more advanced than stock spec and it seems to run a bit stronger, but whether that would benefit yours would depend on the stock distributor curve.